Twine fiber (5)
I believe the answer is:
sisal
'twine fiber' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sisal that I've seen before include "Rope fibre from leaves of tropical plant" , "Rope-fibre made from leaves of tropical plant" , "Hemp fibre" , "Agave yielding fibre" , "Agave fibre found in bad sails" .)