Nuts eaten by buffalo, countless (4)
I believe the answer is:
loco
'nuts' is the definition.
(synonyms)
'eaten by buffalo countless' is the wordplay.
'eaten by' indicates the answer is hidden within the clue.
'LOCO' is hidden in the letters of 'buffalo countless'.
(Other definitions for loco that I've seen before include "Round the bend" , "plant increasing milk yield" , "Slangily crazy" , "Mad - train" , "Crazy; engine" .)