Group of musicians prohibited on radio (4)
I believe the answer is:
band
'group of musicians' is the definition.
(I've seen this before)
'prohibited on radio' is the wordplay.
'prohibited' becomes 'banned' (synonyms).
'on radio' shows a homophone (sound like).
'banned' sounds like 'BAND'.
(Other definitions for band that I've seen before include "troop" , "Players" , "Musicians - gang" , "Musicians - circle" , "Orchestra" .)