Mental acuity (4)
I believe the answer is:
wits
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mental acuity</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 wits that I've seen before include "Intelligence" , "Mental faculties" , "Senses" , "Canniness" , "Keep them about you to stay alert" .)