Not one of the in-crowd (8)
I believe the answer is:
outsider
'not one of the in-crowd' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for outsider that I've seen before include "Someone not accepted by society" , "It's not among the favourites to bet on" , "not a favourite" , "Not a member of the group" , "Unfancied competitor" .)