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' (common abbreviation eg NT for New Testament).
'baby' becomes 'cub' (cub can mean a baby).
'ahead' becomes 'ator' (I can't explain this - if you can you should give a lot more credence to this answer).
'i'+'n'+'cub'+'ator'='INCUBATOR'
'of' acts as a 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" .)