Ask if stall carries alternatives to hemp (5)

I believe the answer is:

sisal

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'hemp' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for sisal that I've seen before include "Agave fibre found in bad sails" , "Strong rope fibre" , "Plant fibre used to make string" , "Fibre-yielding agave" , "material for painter, say?" .)

I've seen this clue in the Sydney Morning Herald.

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