Animal preparing toast (5)
I believe the answer is:
stoat
'animal' is the definition.
(type of rodent)
'preparing toast' is the wordplay.
'preparing' indicates an anagram (the same letters prepared differently).
'toast' is an anagram of 'STOAT'.
(Other definitions for stoat that I've seen before include "Weasel-like mammal" , "Source of ermine" , "Weasel, ermine" , "furry animal" , "Eating rabbit, he" .)