Vehicle hit with its top shearing off (5)
I believe the answer is:
truck
'vehicle' is the definition.
(truck is a kind of vehicle)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for truck that I've seen before include "Lorry - wagon" , "See 14" , "Freight vehicle" , "Vehicle (with which one has no dealings?)" , "Exchange" .)