Back entrance (7)
I believe the answer is:
postern
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">back entrance</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for postern that I've seen before include "Rear entrance" , "private entrance" , "Small gate in the rear of a fort or castle" , "Back gate" , "where tradesmen enter?" .)