Celebrated wildebeests returning (4)
I believe the answer is:
sung
'celebrated' is the definition.
(as opposed to 'unsung')
'wildebeests returning' is the wordplay.
'wildebeests' becomes 'gnus' ('gnu' can be a synonym of 'wildebeest').
'returning' says the letters should be written backwards.
'gnus' reversed gives 'SUNG'.
(Other definitions for sung that I've seen before include "Chinese dynasty; uttered melodiously" , "Performed vocally; Chinese dynasty" , "Celebrated dynasty" .)