Temerity (5)
I believe the answer is:
nerve
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">temerity</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 nerve that I've seen before include "Body fibre conveying sensations to brain" , "Coolness under fire" , "Sauce" , "Courage - cheek" , "Courage, like bodily fibre" .)