Animal's hide can upset (7)
I believe the answer is:
echidna
'animal's' is the definition.
(echidna is a kind of animal)
'hide can upset' is the wordplay.
'upset' is an anagram indicator.
'hide'+'can'='hidecan'
'hidecan' with letters rearranged gives 'ECHIDNA'.
(Other definitions for echidna that I've seen before include "Spiny egg-laying Australian mammal" , "Had nice (anag) -- spiny anteater" , "Such a beast" , "Spiny Aus. mammal" , "Insectivorous mammal" .)