Bad guy's hideout (4)
I believe the answer is:
lair
'bad guy's hideout' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lair that I've seen before include "Private place of seclusion" , "Rail around hiding-place" , "Hideaway, den" , "Supposed large ape, the Bigfoot" , "Home to a wild animal" .)