Bad-tempered companion of Mr Toad (5)
I believe the answer is:
ratty
'bad-tempered' is the definition.
(I've seen this before)
'companion of mr toad' is the wordplay.
I cannot really understand how this works, but
'mr' could be 'ty' and 'ty' is found within the answer.
The remaining letters 'rat' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ratty that I've seen before include "his friend being a dangerous driver" , "Character created by Kenneth Grahame" , "Irritable (colloq.)" , "character on the river bank" , "Characteristic of pest" .)