Swift and quiet in attack (5)
I believe the answer is:
rapid
'swift' is the definition.
(thesaurus)
'quiet in attack' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano').
'in' indicates putting letters inside.
'attack' becomes 'raid' (raiding is a kind of attacking).
'p' placed inside 'raid' is 'RAPID'.
'and' is the link.
(Other definitions for rapid that I've seen before include "Speedy, quick" , "Quickly accomplished" , "Fast, speedy" , "haste" , "Showing pace" .)