Maybe two, four, six and zero still (4,2)
I believe the answer is:
even so
'still' is the definition.
(both can mean 'nonetheless')
'maybe two four six and zero' is the wordplay.
'maybe two four six' becomes 'evens' (even numbers).
'and' is a charade indicator (letters next to each other).
'zero' becomes 'O' (O resembles 0).
'evens'+'o'='EVEN SO'
(Other definitions for even so that I've seen before include "Notwithstanding" , "yet" , "anyway" , "'Nonetheless (4,2)'" , "however" .)