Carving tool commercials on radio (4)
I believe the answer is:
adze
'carving tool' is the definition.
(I've seen this in another clue)
'commercials on radio' is the wordplay.
'commercials' becomes 'ads' (advertisements).
'on radio' shows a homophone (sound like).
'ads' is a homophone of 'ADZE'.
(Other definitions for adze that I've seen before include "One cuts" , "Daze (anag.)" , "Carpenter's tool sounds mathematical" , "Edging tool" , "Wood cutting tool" .)