Not in clique, for start (6)
I believe the answer is:
outset
'start' is the definition.
('outset' can be a synonym of 'start')
'not in clique' is the wordplay.
'not in' becomes 'out' ('out' is the opposite to 'in').
'clique' becomes 'set' (I've seen this before).
'out'+'set'='OUTSET'
'for' is the link.
(Other definitions for outset that I've seen before include "launch" , "Kickoff time?" , "Starting point" , "Beginning, start" , "debut?" .)