Tension (6)
I believe the answer is:
stress
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tension</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for stress that I've seen before include "Lay emphasis on - it's a strain" , "what causes tension" , "possible excuse for sickie?" , "Dwell on" , "Emphasize" .)