Transported goods belong on vehicle (5)
I believe the answer is:
cargo
'transported goods' is the definition.
(I've seen this before)
'belong on vehicle' is the wordplay.
'belong' becomes 'go' (synonyms).
'on' is a charade indicator (letters next to each other).
'vehicle' becomes 'car' (car is a kind of vehicle).
'go' put after 'car' is 'CARGO'.
(Other definitions for cargo that I've seen before include "Shipment" , "What gets carried" , "Freight of ship, plane or truck" , "Hold contents" , "Freight on board ship" .)