Grapefruit hybrid (4)
I believe the answer is:
ugli
'grapefruit hybrid' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ugli that I've seen before include "Tangerine-grapefruit hybrid" , "Large juicy fruit with thick wrinkled skin" , "Cross between Seville orange, grapefruit and tangerine" , "Jamaican form of 6" , "mixed fruit" .)