Fibre in hummus is a legume (5)
I believe the answer is:
sisal
'fibre' is the definition.
(sisal is a kind of fibre)
'in hummus is a legume' is the wordplay.
'in' indicates a hidden word.
'SISAL' can be found hidden inside 'hummus is a legume'.
(Other definitions for sisal that I've seen before include "Plant fibre used to make string" , "material for painter, say?" , "Agave cultivated for its fibre" , "Plant fibre used for ropes" , "Rope fibre from leaves of tropical plant" .)