Ill-natured hybrid (5)
I believe the answer is:
cross
I believe this clue is a double definition.
'ill-natured' is the first definition.
(similar in meaning)
'hybrid' is the second definition.
(cross between two things)
(Other definitions for cross that I've seen before include "winger's pass" , "tangelo for one" , "Thwart, oppose" , "Grouchy" , "Peeved" .)