Vehicle I put on charge (4)
I believe the answer is:
taxi
'vehicle' is the definition.
(taxi is a kind of vehicle)
'i put on charge' is the wordplay.
'put on' means one lot of letters go next to another.
'charge' becomes 'tax' (tax is a kind of charge**).
'i' put after 'tax' is 'TAXI'.
(Other definitions for taxi that I've seen before include "US currency" , "Motor-cab" , "Car for hire" , "Transport for hire" , "Motor vehicle for hire with driver" .)