One new baby, ahead of schedule, turned up here? (9)
I believe the answer is:
incubator
'schedule turned up here?' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'one new baby ahead' is the wordplay.
'one' becomes 'i' (Roman numeral).
'new' becomes 'n' (abbreviation as in New Testament NT).
'baby' becomes 'cub' (cub can mean a baby).
'ahead' becomes 'ator' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'i'+'n'+'cub'+'ator'='INCUBATOR'
'of' is the link.
Can you help me to learn more?
(Other definitions for incubator that I've seen before include "Where to find eggs" , "hospital apparatus" , "Place of growing culture" , "Promotor of growth" , "Apparatus for hatching eggs" .)