Not even rum! (3)
I believe the answer is:
odd
I believe this clue is a double definition.
'not even' is the first definition.
('odd' is the opposite to 'even')
'rum' is the second definition.
(rum can mean strange or dubious)
(Other definitions for odd that I've seen before include "Peculiar sort of number?" , "unlike 1984" , "Eccentric or unpaired" , "like half the numbers?" , "Peculiar in uneven way" .)