Patella's place (4)
I believe the answer is:
knee
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">patella's place</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 knee that I've seen before include "One has a cap" , "Hinged joint" , "This is capped by the patella" , "It jerks reactively" , "Major joint in leg" .)