Charlie meets unknown cleric (5)
I believe the answer is:
canon
'cleric' is the definition.
(I've seen this before)
'charlie meets unknown' is the wordplay.
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
'meets' says to put letters next to each other.
'unknown' becomes 'anon' (I've seen this before).
'c'+'anon'='CANON'
(Other definitions for canon that I've seen before include "Criterion; church official" , "priest for cathedral duties" , "Basic law or principle" , "Member of the clergy" , "Ecclesiastical rule" .)