Rabbit colony (6)
I believe the answer is:
warren
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rabbit colony</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 warren that I've seen before include "Film star Beatty is down with the rabbits" , "Where fast-breeders are at home" , "Network of caves as built by rabbits" , "Rabbit burrow" , "Network of tunnels created by rabbits" .)