Knitting material; long story (4)
I believe the answer is:
yarn
This clue is a double definition.
'knitting material' is the first definition.
(I've seen this in another clue)
'long story' is the second definition.
(Other definitions for yarn that I've seen before include "Story, and thread or wool, say" , "Anecdote" , "Exaggerated story or spun thread" , "Tale; weave" , "Not fully credible story" .)