Fish: it's angry when provoked (8)
I believe the answer is:
stingray
'fish' is the definition.
(stingray is a kind of fish)
'it's angry when provoked' is the wordplay.
'when provoked' is an anagram indicator (I've seen this in other clues).
'its'+'angry'='itsangry'
'itsangry' anagrammed gives 'STINGRAY'.
(Other definitions for stingray that I've seen before include "Dangerous fish" , "swimmer" , "menace in the water" , "TV show" , "Flatfish with barbed spine" .)