Perhaps priest’s circle after Reformation (6)
I believe the answer is:
cleric
'perhaps priest's' is the definition.
'circle after reformation' is the wordplay.
'after reformation' indicates anagramming the letters.
'circle' is an anagram of 'CLERIC'.
(Other definitions for cleric that I've seen before include "One in holy orders" , "Ordained minister" , "Religious official" , "Man of the cloth" , "Person ordained to the Christian ministry" .)