Arid region (6)
I believe the answer is:
desert
'arid region' is the definition.
(I've seen this before)
This is all the clue.
(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" .)