A contrapuntal piece with impact (3)
I believe the answer is:
rap
'impact' is the definition.
(I know that rap is a type of blow)
'a contrapuntal piece with' is the wordplay.
'with' says the answer is hidden in the clue.
'RAP' can be found hidden inside 'contrapuntal piece'.
(Other definitions for rap that I've seen before include "Knock, tap" , "talking during musical performance" , "Hit - "songs" by Snoop Dogg and Jay-Z, say" , "Strike; music genre" , "Pounding" .)