Discovered jackal eating cabbage? (4)
I believe the answer is:
kale
'cabbage?' is the definition.
('kale' can be a synonym of 'cabbage')
'discovered jackal eating' is the wordplay.
'discovered' indicates a hidden word (remove the letters covering the answer in the clue).
'KALE' can be found hidden inside 'jackal eating'.
(Other definitions for kale that I've seen before include "Vegetable" , "Something green" , "Crinkled-leaf cabbage" , "Type of cabbage" , "Cabbage variety" .)