Producer of fibre products is altering bags (5)
I believe the answer is:
sisal
'producer of fibre' is the definition.
'sisal' can be an answer for 'fibre' (sisal is a kind of fibre). I'm not sure about the 'producer of' bit.
'products is altering bags' is the wordplay.
'bags' indicates the answer is hidden within the clue.
'SISAL' is hidden in the letters of 'products is altering'.
Can you help me to learn more?
(Other definitions for sisal that I've seen before include "material for painter, say?" , "Plant fibre used for ropes" , "Rope-fibre made from leaves of tropical plant" , "Fibre used in rope-making" , "Fibre-yielding plant" .)