See about painter turning up ahead of time (5)
I believe the answer is:
early
'ahead of time' is the definition.
('early' can be a synonym of 'ahead of time')
'see about painter turning up' is the wordplay.
'see' becomes 'ely' (example where cathedral located in diocese).
'about' is an insertion indicator.
'painter' becomes 'ra'.
'turning up' says the letters should be written backwards.
'ra' written backwards gives 'ar'.
'ely' going around 'ar' is 'EARLY'.
(Other definitions for early that I've seen before include "before anyone else?" , "Opening" , "Ahead of schedule" , "Beforehand" , "with time to spare?" .)