The den of a wild animal (4)
I believe the answer is:
lair
'the den of a wild animal' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lair that I've seen before include "Supposed large ape, the Bigfoot" , "Rail about wild animal's home" , "Home of a beast" , "enclosure" , "Wild animals' habitation" .)