Doesn't eat the green stuff (6)
I believe the answer is:
leaves
'doesn't eat' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for leaves that I've seen before include "''All the ... are brown'' (California Dreamin')" , "Foliage - goes away" , "some tea, perhaps" , "exits" , "''... of Grass'' (Walt Whitman)" .)