Ankle bone (5)
I believe the answer is:
talus
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ankle bone</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 talus that I've seen before include "Foot's part" , "Ankle bone" , "Ankle-bone" , "Yarns" .)