(O)D&D's Cleric makes sense for (O)D&D, but it makes increasingly less sense outside of the euromedieval milieu. What if you've got a much more immanent and plural divine in your game world than in the euormedieval model and what if there really isn't much of a good/evil, law/chaos thing in your campaign?
Wandering Shinto-Doctor ClassHealth
can wear leather armor without penalty
can use any weapon without penalty, but gunpowder weapons freak out your allies (-4 to Authority)
d6 attack die (I use damage based on class. If you don't like this, then just ignore it)
After Level One (XP/Level and Spell progression as B/X Cleric):
a. bonus to hit starts at one at 3rd level and increases by one at 5th, 7th and 9th level
b. one point training/bonus to two different skills (Advanced Medicine, Archaeology, Occult Knowledge, Paleontology, or Survivalism) at 2nd, 4th, 6th and 8th level
Can "cast" Cleric spells as per Cleric.
At level two, choose or seek out a supernatural ally (think: patron).
Local temples will be home to at least one oni/abdead/elemental/demon/yokai/kami; rural shrines and holy sites work as well. You'll probably have run into one or more during the ramp up to your second level. You can pick a new ally or gain an additional ally every time you gain access to a new spell level
For each ally, the player can suggest a monster type (outsider/abdead/elemental/demon/yokai) and a name if one or both aren't already known. GM gets the final call and some already known entities may not be willing to aid you.
Your ally gives you a charm, fang, hair, feather, tattoo, scar (physical, spiritual, psychological), vial of ecto(cyto?)plasm or vital fluids, bit of skin, finger, etc., etc. To "cast" a spell from the Cleric list, you hold/touch/kiss/whatever the implement and invoke the will of your ally and they act through you. You'll work out what implement with your GM (suggest something if you want, otherwise the GM will make a suggestion). If you can't think of something right away, maybe come up with a vague placeholder and then fill in the blanks later.
Authority (replaces Turning)
Roll d20 + number of spells available yet to cast today - 4
Call on the authority of your allies and attempt to argue/plead/reason with one or more outsider/abdead/demon/oni/yokai as if you and it were on the same level. Discourse occurs in the pre-language spoken by all such creatures and is not properly telepathic or audible. Discourse is with the leader or leaders of the group (combine HD if more than one). If the roll results in a number equal to or greater than the total HD of the opposing side, they will "settle down," depart, or simply sit down, frustrated. Bonus points for making an argument the GM considers would be persuasive to the opposing side. Takes a d3+1 rounds to complete conversation. No limit on uses. Lesser beings will likely follow the lead of their more powerful cohort, but not always. Can always be used to communicate with these kinds of creatures, if not sway them. Can occasionally be used to read pre-language scrolls, maps, puzzle glyphs, and the like. Higher beings (not the garden variety kami) are likely reachable by Commune only and attempts to use Authority on them will immediately fail (your allies know better, even if you don't).
ALTERNATE/PRO RULECleric spells are limited by the particular ally type, as determined by GM, but a general guideline might be:
elemental allies grant access to resist cold, light, resist fire, continual light, create water, create food, striking, quest, commune
outsider/demon/oni/yokai allies grant access to cure spells (inc diseases), protection from... spells, remove fear, Bless, speak with animals, remove curse, Dispel Evil and Raise Dead and all their related opposites; also, quest and commune
abdead allies would grant "medium tapping the underworld"-type magic: detect spells, protection from..., know alignment, find traps, silence, snake charm, locate object, growth of animals, speak with plants, sticks to snakes, commune, insect plague, quest and raise dead.
Outsider/demon/oni/yokai are likely the most commonly encountered divine being/kami/potential supernatural ally followed closely by the elemental allies and then, least common by far, are abdead allies, which are likely super-undead (the ghost of a demilich, the corporate spirit of the many generations of dead of a village, the ancestors of the God-emperor, the spirit of a long forgotten but powerful kami).
If you use this rule, I've found it's best to also not require the player to pick for which spells their character has prayed and instead treat Cleric casting and Sorcerer casting (spontaneous use of "spell slots").
(I'll save how I have protection and alignment work sans good/evil, law/chaos for another post).
painting by Rozefire.