Return of tailless bird provides something to chew over (3)
I believe the answer is:
cud
'something to chew over' is the definition.
(I've seen this in another clue)
'return of tailless bird' is the wordplay.
'return of' says the letters should be written backwards.
'tailless' means to remove the last letter (the tail of the word is removed).
'bird' becomes 'duck' (duck is a kind of bird).
'duck' with its last letter taken away is 'duc'.
'duc' written backwards gives 'CUD'.
'provides' acts as a link.
(Other definitions for cud that I've seen before include "Something to be chewed" , "it's still in the cow" , "It's chewed by a ruminant" , "It's partly digested and chewed again" , "Cows chew it" .)