Enthuse to new bird (5)
I believe the answer is:
raven
'bird' is the definition.
(raven is a kind of bird)
'enthuse to new' is the wordplay.
'enthuse' becomes 'rave' (I've seen this in another clue).
'to new' becomes 'n' (abbreviation as in New Testament NT).
'rave'+'n'='RAVEN'
(Other definitions for raven that I've seen before include "pig" , "Glossy black colour" , "Bird of ill omen" , "Crow-like bird" , "Largest member of crow family" .)