A quiet craft by itself (5)
I believe the answer is:
apart
'by itself' is the definition.
(I've seen this in another clue)
'a quiet craft' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'craft' becomes 'art' (both can mean cunning or trickery).
'a'+'p'+'art'='APART'
(Other definitions for apart that I've seen before include "Separate in a trap" , "divorced" , "in bits" , "in isolation" , "away" .)