Illegal trade (5,6)
I believe the answer is:
black market
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">illegal trade</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 black market that I've seen before include "Dodgy dealing" , "Selling in violation of controls" , "Place to purchase illicit goods" , "Covert trade in illicit goods" , "Illegal system of trade" .)