Quick and quiet in attack (5)
I believe the answer is:
rapid
'quick' is the definition.
(synonyms)
'quiet in attack' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'in' is an insertion indicator.
'attack' becomes 'raid' (raid is a kind of attack).
'p' going into 'raid' is 'RAPID'.
'and' acts as a link.
(Other definitions for rapid that I've seen before include "Quickly accomplished" , "Zippy" , "Speedy, quick" , "Showing pace" , "Prompt" .)