Nervousness (7)
I believe the answer is:
tension
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">nervousness</span>' is the definition.<br/ ><span class="explanation-format__explanation">(feeling tense)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tension that I've seen before include "State of strain or suspense" , "nerves" , "Nervous strain" , "Uneasiness" , "The effect of force exerted in or on something" .)