Tax-free zone (5,7)
I believe the answer is:
black economy
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tax-free zone</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 economy that I've seen before include "untaxed zone" , "Tax-free zone" , "A nation's illegally undeclared income" , "It produces illegally undeclared income" , "Unrecorded and untaxed dealings" .)