Fast and quiet in attack (5)
I believe the answer is:
rapid
'fast' is the definition.
(similar in meaning)
'quiet in attack' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'in' indicates putting letters inside.
'attack' becomes 'raid' (raiding is a kind of attacking).
'p' placed into 'raid' is 'RAPID'.
'and' acts as a link.
(Other definitions for rapid that I've seen before include "Quickly accomplished" , "Fast, speedy" , "Happening at great speed" , "Happening quickly" , "Moving at speed" .)