Knitting instruments small and unnecessary (8)
I believe the answer is:
needless
'unnecessary' is the definition.
(similar in meaning)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for needless that I've seen before include "uncalled for" , "luxury" , "Unnecessary, avoidable" , "Surplus to requirements" , "Uncalled-for" .)