Quiet member of the clergy with trouble is to prove superior (7)
I believe the answer is:
prevail
'to prove superior' is the definition.
(I've seen this before)
'quiet member of the clergy with trouble' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'member of the clergy' becomes 'rev' (short for reverend).
'with' is a charade indicator (letters next to each other).
'trouble' becomes 'ail' (synonyms).
'p'+'rev'+'ail'='PREVAIL'
'is' acts as a link.
(Other definitions for prevail that I've seen before include "get the upper hand" , "come out on top" , "Win through" , "Gain mastery" , "Be victorious" .)