Hear about bird (4)
I believe the answer is:
rhea
'bird' is the definition.
(rhea is a kind of bird)
'hear about' is the wordplay.
'about' is an anagram indicator.
'hear' is an anagram of 'RHEA'.
(Other definitions for rhea that I've seen before include "Flightless bird -- satellite of Saturn" , "Ostrich-like bird - satellite of Saturn" , "Grounded bird" , "Flightless bird - Greek fertility goddess" , "New World ostrich" .)