Angry, extremely hostile sheep (3,2)
I believe the answer is:
het up
'angry' is the definition.
('het up' can be similar in meaning to 'angry')
'extremely hostile sheep' is the wordplay.
'extremely' suggests removing the centre.
'sheep' becomes 'tup' (tup is a kind of sheep).
'hostile' with its centre taken out is 'he'.
'he'+'tup'='HET UP'
(Other definitions for het up that I've seen before include "in a state" , "Angry - excited" , "On edge - agitated" , "Indignant" , "Irate" .)