Opening in a garment (7)
I believe the answer is:
armhole
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">opening in a garment</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 armhole that I've seen before include "part of jacket" , "Garment aperture" , "Jacket opening" , "Space" , "Garment opening" .)