Triumph for quiet priest with trouble (7)
I believe the answer is:
prevail
'triumph' is the definition.
(I know that triumph can be written as prevail)
'quiet priest with trouble' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'priest' becomes 'rev' (short for reverend).
'with' says to put letters next to each other.
'trouble' becomes 'ail' (synonyms).
'p'+'rev'+'ail'='PREVAIL'
'for' is the link.
(Other definitions for prevail that I've seen before include "get the upper hand" , "Be widespread; prove superior" , "Exist generally" , "Be victorious" , "Win through" .)