Inexhaustible (10)
I believe the answer is:
bottomless
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">inexhaustible</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 bottomless that I've seen before include "Having no limits" , "Unfathomable" , "Inexhaustible" , "without 17 [BEHINDS] !" , "never getting used up?" .)