Movement of vehicles (7)
I believe the answer is:
traffic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">movement of vehicles</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for traffic that I've seen before include "Vehicles coming and going" , "Movement along a route" , "Deal illegally in vehicles?" , "What uses road" , "Trade (in cars?)" .)