Restricted zone (2-2,4)
I believe the answer is:
no-go area
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">restricted 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 no-go area that I've seen before include "Off-limits district" , "It's taboo to enter" , "Prohibited zone" , "Forbidden zone" , "Place where entry is dangerous or forbidden" .)