Rejecting outsiders, members upset true selves (4)
I believe the answer is:
egos
'selves' is the definition.
('ego' can be a synonym of 'self')
'rejecting outsiders members upset true' is the wordplay.
'rejecting' is a reversal indicator.
'outsiders members' becomes 'ge' (I can't explain this - if you can you should believe this answer much more).
'upset' says the letters should be written in reverse.
'true' becomes 'so' (similar in meaning).
'ge' written backwards gives 'eg'.
'so' in reverse letter order is 'os'.
'eg'+'os'='EGOS'
Can you help me to learn more?
(Other definitions for egos that I've seen before include "feelings of self-importance" , "People's personal pride - the parts of them that are conscious" , "Lots of self-esteem" , "Self-images" .)