Ascot perhaps is down river (8)
I believe the answer is:
neckwear
'ascot perhaps' is the definition.
(ascot is a kind of neckwear)
'down river' is the wordplay.
'down' becomes 'neck' (both can mean to finish a drink).
'river' becomes 'wear' (river in the north east of England).
'neck'+'wear'='NECKWEAR'
'is' acts as a link.
(Other definitions for neckwear that I've seen before include "could be a tie" , "sort of clothing" , "Collars, ties etc." , "Tie perhaps" , "Stock" .)