Odd's opposite (4)
I believe the answer is:
even
'odd's opposite' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for even that I've seen before include "Crisp and ---, how King Wenceslas found the snow" , "Smooth, uniform in quality" , "Pantomime" , "Stable" , "Going so far as to" .)