Toast cooked by animal (5)
I believe the answer is:
stoat
'animal' is the definition.
(type of rodent)
'toast cooked' is the wordplay.
'cooked' indicates an anagram (letters cooked into a new form).
'toast' with letters rearranged gives 'STOAT'.
'by' acts as a link.
(Other definitions for stoat that I've seen before include "Weasel, ermine" , "Short-tail weasel" , "Source of ermine" , "Weasel-like mammal" , "Small carnivore" .)