Cross: a little indignant, I go nuts! (5)
I believe the answer is:
tigon
'cross' is the definition.
(offspring of a lion and a tiger)
'a little indignant i go nuts' is the wordplay.
'a little' says the answer is hidden in the clue.
'TIGON' is hidden within 'indignant i go nuts'.
(Other definitions for tigon that I've seen before include "Tiger-lion hybrid" , "cat cross" , "Big hybrid of the cat family" , "Animal" , "Hybrid offspring of two big cats" .)