Fine strand or yarn (6)
I believe the answer is:
thread
I believe this is a double definition.
'fine strand' is the first definition.
(I've seen this before)
'yarn' is the second definition.
(synonyms)
(Other definitions for thread that I've seen before include "Yarn, string" , "Strand of, eg, cotton" , "Dearth (anag)" , "Strand of cotton or other fibre" , "What sewer takes" .)