Bird seen around end of dawn chorus (5)
I believe the answer is:
'chorus' is the definition.
'bird seen around end of dawn' is the wordplay.
'bird' becomes 'chat' (chat is a kind of bird).
'seen around' indicates putting letters inside.
'end of' suggests the final letters.
The last letter of 'dawn' is 'n'.
'chat' placed around 'n' is 'CHANT'.
(Other definitions for chant that I've seen before include "Sing" , "Intone - recite" , "Repeated rhythmic song" , "Repetitious sung slogan" , "A monotonous song or rhythmic call" .)