Unfashionable crowd at the start (6)
I believe the answer is:
outset
'the start' is the definition.
('outset' can be a synonym of 'start')
'unfashionable crowd' is the wordplay.
'unfashionable' becomes 'out' ('out' can be a synonym of 'unfashionable').
'crowd' becomes 'set' (I've seen this in other clues).
'out'+'set'='OUTSET'
'at' acts as a link.
(Other definitions for outset that I've seen before include "Kickoff time?" , "Opening stage" , "Beginning, start" , "Inception" , "origin" .)