Excise duty applied to one vehicle (4)
I believe the answer is:
taxi
'vehicle' is the definition.
(taxi is a kind of vehicle)
'excise duty applied to one' is the wordplay.
I cannot really see how this works, but
'excise' could be 'tax' (I've seen this in another clue) and 'tax' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
No letters remain.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for taxi that I've seen before include "Move along a runway" , "Public service vehicle" , "Motor-cab" , "move on ground before take-off" , "Prepare to fly" .)