Agave fibre (8)
'agave fibre' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sisal that I've seen before include "Agave cultivated for its fibre" , "Fibre used in rope-making" , "Fibre-yielding plant" , "Fibre of Mexican agave" , "Ropemaker" .)
(Another definition for henequen that I've seen is " plant".)