Cud-chewing mammal (8)
I believe the answer is:
ruminant
'cud-chewing mammal' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ruminant that I've seen before include "Cud-chewing animal" , "contemplative" , "contemplating" , "Goat, say" , "Mammal that chews the cud" .)