Young hawk broke finally with utter reversal (4)
I believe the answer is:
eyas
'young hawk' is the definition.
(I've seen this in another clue)
'broke finally with utter reversal' is the wordplay.
'finally' says to take the final letters.
'with' is a charade indicator (letters next to each other).
'utter' becomes 'say' (to utter something is to speak or say it).
'reversal' says the letters should be written backwards.
The last letter of 'broke' is 'e'.
'say' written backwards gives 'yas'.
'e'+'yas'='EYAS'
(Other definitions for eyas that I've seen before include "Nestling hawk" , "Unfledged hawk" , "Nestling falcon" , "Young bird" , "Nestling bird" .)