Prohibited group, so we hear (6)
I believe the answer is:
banned
'prohibited' is the definition.
(synonyms)
'group so we hear' is the wordplay.
'group' becomes 'band' (band can mean a group of people).
'so we hear' indicates a 'sounds like' (homophone) clue.
'band' sounds like 'BANNED'.
(Other definitions for banned that I've seen before include "Forbidden by law" , "Taboo" , "Outlawed" , "Group on radio" , "Legally prohibited" .)