A levy is on vehicles (5)
I believe the answer is:
taxis
'vehicles' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Maybe you can see a link between them that I don't see?
'a levy is on' is the wordplay.
'a levy' becomes 'tax' (tax is a kind of levy).
'on' says to put letters next to each other.
'tax'+'is'='TAXIS'
Can you help me to learn more?
(Other definitions for taxis that I've seen before include "return to right place" , "Cabs" , "Cars with a driver for hire" .)