Tauten (7)
I believe the answer is:
tighten
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tauten</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tighten that I've seen before include "Make (rope) less slack" , "contract" , "To improve focus" , "Fasten more firmly" , "Stiffen" .)