Church dignitary that could make power tell (7)
I believe the answer is:
prelate
'church dignitary' is the definition.
(I've seen this before)
'power tell' is the wordplay.
'power' becomes 'p'.
'tell' becomes 'relate' (relating is a kind of telling).
'p'+'relate'='PRELATE'
'that could make' acts as a link.
(Other definitions for prelate that I've seen before include "Cleric" , "Church high-ranker" , "priest" , "Senior churchman" , "Bishop or other ecclesiastical dignitary" .)