Midnight or noon (6)
I believe the answer is:
twelve
This clue is a double definition.
'midnight' is the first definition.
(I've seen this before)
'noon' is the second definition.
(synonyms)
(Other definitions for twelve that I've seen before include "Six twos" , "houses in a year?" , "Half the number here" , "Apostles and members of the jury" , "Lunchtime" .)