Transport gives endless concern (3)
I believe the answer is:
car
'transport' is the definition.
(car is a kind of transport)
'endless concern' is the wordplay.
'endless' means to remove the last letter.
'concern' becomes 'care' ('care' can be a synonym of 'concern').
'care' with its final letter taken off is 'CAR'.
'gives' is the link.
(Other definitions for car that I've seen before include "Auto" , "Automobile" , "Conveyance" , "Hatchback, say?" , "saloon perhaps" .)