Society girl, a right leftie getting banned (8)
I believe the answer is:
debarred
'banned' is the definition.
(thesaurus)
'society girl a right leftie getting' is the wordplay.
'society girl' becomes 'deb' (I've seen this in another clue).
'a right' becomes 'ar' (I've seen this in other clues).
'leftie' becomes 'red' (red can informally mean communist).
'getting' is a charade indicator (letters next to each other).
'deb'+'ar'+'red'='DEBARRED'
(Other definitions for debarred that I've seen before include "not allowed!" , "Excluded, ruled out" , "Kept out" .)