Leave single thread (6)
I believe the answer is:
strand
I believe this clue is a double definition.
'leave' is the first definition.
(I know that strand is a more specific form of the action abandon)
'single thread' is the second definition.
(I've seen this in another clue)
(Other definitions for strand that I've seen before include "Thread - abandon" , "Beach - fibre" , "Maroon - filament" , "Thread; leave in lurch" , "that may be found by the sea" .)