Animal with a bad temper -- he creates disaster (11)
I believe the answer is:
catastrophe
'disaster' is the definition.
('catastrophe' can be a synonym of 'disaster')
'animal with a bad temper he' is the wordplay.
'animal with' becomes 'cat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'bad temper' becomes 'strop' (I've seen this before).
'cat'+'a'+'strop'+'he'='CATASTROPHE'
'creates' acts as a link.
Can you help me to learn more?
(Other definitions for catastrophe that I've seen before include "Utter disaster" , "Terrible event" , "Calamity" , "Great disaster" , "Denouement" .)