Puts on commercials on the radio (4)
I believe the answer is:
adds
'puts on' is the definition.
(I've seen this before)
'commercials on the radio' is the wordplay.
'commercials' becomes 'ads' (I've seen this before).
'on the radio' indicates a 'sounds like' (homophone) clue.
'ads' is a homophone of 'ADDS'.
(Other definitions for adds that I've seen before include "Tots up" , "Supplements" , "Sums, totals" , "Finds the sum (4)," , "Puts (numbers) together" .)