Young hawk in European state making a comeback (4)
I believe the answer is:
eyas
'young hawk' is the definition.
(I've seen this in another clue)
'european state making a comeback' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'state' becomes 'say' (to state something is to say it).
'making a comeback' says the letters should be written backwards.
'say' backwards is 'yas'.
'e'+'yas'='EYAS'
'in' is the link.
(Other definitions for eyas that I've seen before include "Young bird" , "Nestling falcon" , "Young falcon" , "Nestling bird" , "young hawk" .)