Vehicle run for freight (5)
I believe the answer is:
cargo
'freight' is the definition.
('cargo' can be a synonym of 'freight')
'vehicle run' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'run' becomes 'go' ('go' can be a synonym of 'run').
'car'+'go'='CARGO'
'for' acts as a link.
(Other definitions for cargo that I've seen before include "Goods carried on ship or plane" , "Hold contents" , "Freight, load" , "Freight of ship, plane or truck" , "Goods carried by vessel or vehicle" .)