Not even strange (3)
I believe the answer is:
odd
This clue is a double definition.
'not even' is the first definition.
('odd' is the opposite to 'even')
'strange' is the second definition.
(I know that strange can be written as odd)
(Other definitions for odd that I've seen before include "Peculiar sort of number?" , "Peculiar or eccentric" , "like half the numbers?" , "Unusual, strange" , "Queer" .)