Vehicle — look! Right on track (5)
I believe the answer is:
lorry
'vehicle' is the definition.
(lorry is a kind of vehicle)
'look right on track' is the wordplay.
'look' becomes 'lo'.
'right' becomes 'r' (common abbreviation).
'on' is a charade indicator (letters next to each other).
'track' becomes 'ry'.
'lo'+'r'+'ry'='LORRY'
(Other definitions for lorry that I've seen before include "Heavy goods vehicle" , "HGV" , "From which stolen goods fall?" , "Load-carrying vehicle" , "Large truck" .)