Outlawed pop group on radio (6)
I believe the answer is:
banned
'outlawed' is the definition.
(banning is a kind of outlawing)
'pop group on radio' is the wordplay.
'pop group' becomes 'band' (I've seen this before).
'on radio' shows a homophone (sound like).
'band' sounds like 'BANNED'.
(Other definitions for banned that I've seen before include "Group on radio" , "Prohibited officially" , "expelled" , "Censored" , "Forbidden by law" .)