/ ˈwɒnə; NAmE ˈwɑːnə; ˈwɔːnə; ˈwʌnə/
( informal , non-standard ) the written form of the word some people use to mean 'want to' or 'want a', which is not considered to be correct :
I wanna go.
Wanna drink? (= Do you want ... )
HELP NOTE : You should not write this form, unless you are copying somebody's speech.