Midday or midnight? (6)
I believe the answer is:
twelve
This clue is a double definition.
'midday' is the first definition.
(I've seen this in another clue)
'midnight?' is the second definition.
(I've seen this in another clue)
(Other definitions for twelve that I've seen before include "[MIDNIGHT], perhaps" , "Highest number on clock" , "Apostles and members of the jury" , "AM/PM separator?" , "The midnight hour" .)