Cows chew it (3)
I believe the answer is:
cud
'cows chew it' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cud that I've seen before include "It's chewed by a ruminant" , "It's partly digested and chewed again" , "Ruminants chew it (3)" , "it's still in the cow" , "result of some rumination" .)