Old English clerc, from Late Latin clericus "a priest," from Greek klerikos (adj.) in church jargon "of the clergy," derived from kleros "lot, inheritance" (originally "a shard or wood chip used in casting lots," related to klan "to break;" see holt), used by early Greek Christians for matters relating to ministry based on Deut. xviii:2 reference to Levites as temple assistants: "Therefore shall they have no inheritance among their brethren: the Lord is their inheritance," kleros being used as a translation of Hebrew nahalah "inheritance, lot."
If the word choice was meant to remind clerics of anything, however, the reminder was lost with the knowledge of ancient Greek. Or else it is from the use of the word in Acts i:17. Modern bureaucratic usage is from c.1500, a reminder of the dark ages when clergy alone could read and write. Related: Clerkship.