Steal animal's morsel (7)
I believe the answer is:
snippet
'morsel' is the definition.
(thesaurus)
'steal animal's' is the wordplay.
'steal' becomes 'snip' (I've seen this before).
'animal' becomes 'pet' (pet is a kind of animal).
'snip'+'pet'='SNIPPET'
(Other definitions for snippet that I've seen before include "Brief extract" , "A small piece cut off" , "Short extract" , "Bit (of info?)" , "Small scrap" .)