... film award for outsize vehicle (5)
I believe the answer is:
oscar
'film award' is the definition.
(I've seen this before)
'outsize vehicle' is the wordplay.
'outsize' becomes 'os'.
'vehicle' becomes 'car' (car is a kind of vehicle).
'os'+'car'='OSCAR'
'for' is the link.
(Other definitions for oscar that I've seen before include "- - Hammerstein (musicals)" , "Film prize" , "Annual film award" , "The familiar Mr Wilde, playwright" , "Comms code for "O"" .)