Go with Jack to reverse vehicle (4)
I believe the answer is:
jeep
'vehicle' is the definition.
(jeep is a kind of vehicle)
'go with jack to reverse' is the wordplay.
'go' becomes 'pee' (both can mean to urinate).
'with' is a charade indicator (letters next to each other).
'jack' becomes 'J' (playing card abbreviation).
'to reverse' says the letters should be written backwards.
'pee'+'j'='peej'
'peej' reversed gives 'JEEP'.
(Other definitions for jeep that I've seen before include "Sturdy vehicle" , "Small four-wheel drive vehicle" , "Military four-wheel-drive vehicle" , "Truck" , "Vehicle for rough terrain" .)