Quiet melody put together (4)
I believe the answer is:
pair
'put together' is the definition.
(I've seen this in another clue)
'quiet melody' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'melody' becomes 'air' (synonyms).
'p'+'air'='PAIR'
(Other definitions for pair that I've seen before include "Cereal used as food" , "Brace, couple" , "Two ducks in one game of cricket" , "flight of stairs" , "Put together - two of a kind" .)