Rabbit hole (6)
I believe the answer is:
burrow
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rabbit hole</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for burrow that I've seen before include "Tunnel; animal shelter" , "Hole dug by a rabbit" , "A rabbit's tunnel" , "Rabbit's hole" , "Tunnel made by rabbit" .)