Quietly tell church dignitary (7)
I believe the answer is:
prelate
'church dignitary' is the definition.
(I've seen this before)
'quietly tell' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'tell' becomes 'relate' (relating is a kind of telling).
'p'+'relate'='PRELATE'
(Other definitions for prelate that I've seen before include "Senior member of the clergy" , "Church high-ranker" , "High church dignitary" , "High-ranking clergyman" , "Pleater (anag.)" .)