Bit quiet, you say? (5)
I believe the answer is:
piece
'bit' is the definition.
(synonyms)
'quiet you say?' is the wordplay.
'quiet' becomes 'peace' (I've seen this before).
'you say?' indicates a 'sounds like' (homophone) clue.
'peace' sounds like 'PIECE'.
(Other definitions for piece that I've seen before include "Portion; musical work" , "Fragment" , "rook, perhaps" , "Castle, perhaps" , "newspaper article" .)