Was aware of talking animal (3)
I believe the answer is:
gnu
'animal' is the definition.
(thesaurus)
'was aware of talking' is the wordplay.
'was aware of' becomes 'knew' (I've seen this before).
'talking' shows a homophone (sound like).
'knew' is a homophone of 'GNU'.
(Other definitions for gnu that I've seen before include "Strange gun for an antelope" , "hitherto unknown, we hear" , "animals" , "Literally wild beast" , "Gun to get antelope" .)