They're like ostriches, but get a different share (5)
I believe the answer is:
rheas
'they're like ostriches but' is the definition.
The definition suggests an adverb but the answer is not.
'a different share' is the wordplay.
'a different' indicates an anagram (letters placed in a different order).
'share' is an anagram of 'RHEAS'.
'get' is the link.
Can you help me to learn more?
(Other definitions for rheas that I've seen before include "these birds won't fly" , "Ostrich-like birds" , "Flightless birds" .)