Angry mule? (5)
I believe the answer is:
cross
I believe this is a double definition.
'angry' is the first definition.
(cross can mean annoyed or angry)
'mule?' is the second definition.
(mules are crossbreeds)
(Other definitions for cross that I've seen before include "Sign - angry" , "religious symbol" , "Angry; thwart" , "Frustrate" , "Eg, saltire" .)