Lower leg joint (5)
I believe the answer is:
ankle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lower leg joint</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 ankle that I've seen before include "Narrow part of leg" , "Lower leg joint" , "Low joint" , "Leg-joint" , "Bone over foot" .)