Strong tightly twisted cotton thread (5)
I believe the answer is:
lisle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">strong tightly twisted cotton thread</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for lisle that I've seen before include "Strong cotton material" , "Cotton stocking thread" , "Strong tightly twisted cotton thread" , "Fine cotton thread used in stockings" , "Strong twisted cotton thread for the strange Ellis" .)