Arid region (6)
I believe the answer is:
desert
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">arid region</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 desert that I've seen before include "See 1" , "Merit < leave" , "Run away from the forces; desolate" , "Leave in the lurch" , "Arid region with little or no vegetation" .)