Deal with vehicles on the road (7)
I believe the answer is:
traffic
This clue is a double definition.
'deal' is the first definition.
(to traffic something is to sell or deal in it)
'vehicles on the road' is the second definition.
(I've seen this before)
'with' is the link.
(Other definitions for traffic that I've seen before include "Movement along a route" , "Dishonest trading" , "dealings" , "Flow of vehicles" , "Deal illegally , in drugs say" .)