Worry about returning odd bits of yellow fabric (9)
I believe the answer is:
polyester
'fabric' is the definition.
(polyester is a kind of fabric)
'worry about returning odd bits of yellow' is the wordplay.
'worry' becomes 'pester' (I can't justify this - if you can you should believe this answer much more).
'about' means one lot of letters goes inside another.
'returning' is a reversal indicator.
'odd bits of' indicates alternate letters.
The alternating letters of 'yellow' are 'ylo'.
'ylo' backwards is 'oly'.
'pester' going around 'oly' is 'POLYESTER'.
Can you help me to learn more?
(Other definitions for polyester that I've seen before include "Synthetic fibre or substance" , "This material goes out to Presley" , "Synthetic textile" , "Man-made fibre" , "Stole prey (anag) - synthetic material" .)