Reject not in group performing play (7)
I believe the answer is:
outcast
'reject' is the definition.
(I've seen this before)
'in group performing play' is the wordplay.
'in group performing' becomes 'out' (I can't explain this - if you can you should believe this answer much more).
'play' becomes 'cast' (cast is a kind of play).
'out'+'cast'='OUTCAST'
'not' is the link.
Can you help me to learn more?
(Other definitions for outcast that I've seen before include "Pariah, society reject" , "untouchable" , "Pariah, one rejected by society" , "Person rejected by a group or society" , "One is excluded from society" .)