Constrict (7)
I believe the answer is:
tighten
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">constrict</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that constrict is a more specific form of the action the tighten)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tighten that I've seen before include "becoming tense" , "Make less loose" , "Constrict" , "Make (rope) less slack" , "Restrict" .)