Cleric is a title for a person in a position of dispensing knowledge and understanding about religion or other spiritual matters, or in a position of authority to determine the proper application of spiritual rules.
History and specifics[]
Members of the Bajoran religion were referred to as clerics, as were the Klingons of Boreth and the Cardassians of the Oralian Way. (DS9 novel: This Gray Spirit, TNG episode: "Rightful Heir", DS9 novel: Bajor: Fragments and Omens)
Jeshoh was a Yrythny cleric. (DS9 novel: This Gray Spirit
Clerics deciding the fate of a suspected witch.
Clerics were the theocratic authority on Goran IV. They wore violet-colored robes with conical helmets that completely covered their heads and faces. They were armed with hooked staffs that were used to capture individuals and render them unconscious, if need be. Clerics held their prisoners in the Cathedral, a fortress-like structure. They also served as executioners, often using trial-by-water to drown suspected witches. Captain Kirk, Mr. Spock and Doctor McCoy were captured by the Clerics on Stardate 8124.2 during a mission on Goran IV. (TOS comic: "The Long Night's Dawn!")
A fictional alien humanoid, Zaka, held the title of cleric in a diplomatic holoprogram variant of the Kobayashi Maru scenario in the year 2401. (PIC - Stargazer comic: "Issue 1")