Muffet's fare (4)
I believe the answer is:
whey
'muffet's fare' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for whey that I've seen before include "part of natural drink" , "11 Across residue" , "Watery content of milk" , "Watery residue of milk" , "Separated part of milk" .)