Strong thread (5)
I believe the answer is:
twine
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">strong thread</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for twine that I've seen before include "twist" , "Knot" , "Curl; string" , "Garden string" , "wind" .)