Not taut; loose (5)
I believe the answer is:
slack
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">not taut</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">loose</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that loose can be written as slack)</span><br/ ><br/ ></span>
(Other definitions for slack that I've seen before include "Idle and disinclined to work" , "Limp - negligent" , "Not taut" , "skive" , "Flaccid" .)