Leafy green vegetables (8)
I believe the answer is:
cabbages
'leafy green vegetables' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cabbages that I've seen before include "Greens" , "Begs a cab to get vegetables" , "heads for kitchen" , "Of shoes and ships and ceiling wax,/ of . . . . . . . . and kings (Through the Looking Glass)" , "Leafy green vegetables" .)