Quietly rewrite the phrase, maybe (7)
I believe the answer is:
perhaps
'maybe' is the definition.
(synonyms)
'quietly rewrite the phrase' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'rewrite' indicates anagramming the letters.
'phrase' anagrammed gives 'erhaps'.
'p'+'erhaps'='PERHAPS'
(Other definitions for perhaps that I've seen before include "Conceivably" , "Possibly, maybe" , "Not necessarily" , "say" , "Quite possibly" .)