Extremity, bound (5)
I believe the answer is:
limit
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">extremity</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(limit is a kind of extremity)</span><br/ ><br/ >'<span class="explanation-format__original">bound</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(limit is a kind of bound)</span><br/ ><br/ ></span>
(Other definitions for limit that I've seen before include "Constrain" , "Put restriction on" , "Boundary, demarcation line" , "Hem in" , "speed restriction applied" .)