Someone who may act weird and not even dance (7)
I believe the answer is:
oddball
'someone who may act weird' is the definition.
'not even dance' is the wordplay.
'not even' becomes 'odd' ('odd' is the opposite to 'even').
'dance' becomes 'ball' (ball is a kind of dance).
'odd'+'ball'='ODDBALL'
'and' acts as a link.
(Other definitions for oddball that I've seen before include "Eccentric person like uneven sphere" , "eccentric type" , "Weird" , "Eccentric person like peculiar sphere" , "case" .)