Den of a wild animal (4)
I believe the answer is:
lair
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">den of a wild animal</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for lair that I've seen before include "Animal's resting place" , "Place to hide" , "Waylay" , "Secret base" , "Rail around hiding-place" .)