Hears about creatures (5)
I believe the answer is:
rheas
'creatures' is the definition.
(rhea is a kind of creature)
'hears about' is the wordplay.
'about' indicates an anagram.
'hears' with letters rearranged gives 'RHEAS'.
(Other definitions for rheas that I've seen before include "Ostrich-like birds" , "Flightless birds" , "these birds won't fly" .)