Vehicle not working? Not quite (3)
I believe the answer is:
bus
'vehicle' is the definition.
(bus is a kind of vehicle)
'not working? not quite' is the wordplay.
'not working?' becomes 'bust' (bust can mean broken).
'not quite' means to remove the last letter.
'bust' with its last letter removed is 'BUS'.
(Other definitions for bus that I've seen before include "Means of public transport" , "Large passenger vehicle - small business!" , "Something caught" , "Charabanc" , "Coach" .)