Tautness (7)
I believe the answer is:
tension
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tautness</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tension that I've seen before include "Nervous strain" , "Stretched, uneasy, condition" , "Stretched state" , "A pulling strain" , "The effect of force exerted in or on something" .)