Pet ate in RSPCA compound (7,3)
I believe the answer is:
persian cat
'pet' is the definition.
(I have seen 'Hairy pet' mean 'persian cat' so perhaps 'pet' could also mean 'persian cat')
'ate in rspca compound' is the wordplay.
'compound' indicates an anagram.
'ate'+'in'+'rspca'='ateinrspca'
'ateinrspca' anagrammed gives 'PERSIAN CAT'.
(Other definitions for persian cat that I've seen before include "Hairy pet" , "beast" , "animal" , "domestic pet" .)