Business traffic (5)
I believe the answer is:
trade
This clue is a double definition.
'business' is the first definition.
(I know that trade is a type of business)
'traffic' is the second definition.
(traffic can mean illegal trade)
(Other definitions for trade that I've seen before include "job" , "Barter, do business" , "Dealings, business" , "Buying and selling of goods" , "Barter or swap" .)