A bird and part of another one (5)
I believe the answer is:
heron
'a bird' is the definition.
(I know that heron is a type of bird)
'part of another one' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'HERON' can be found hidden inside 'another one'.
'and' is the link.
(Other definitions for heron that I've seen before include "Rhone (anag) - bird" , "Bird of the Rhone, strangely" , "Big bird" , "Grey or white long-legged wading bird" , "Tall wading bird" .)