Can it be Wino nie jest obiadem?
Not, "obiad" means dinner. "Posiłek" is used while you're thinking about breakfast/lunch/dinner/supper, but don't precise it.
Could be wino nie jest posiłkiem, but not obiadem when translating English ‘meal’.
I put 'Nie wino jest posiłkiem', why is this wrong?
That's like "It is not wine that is a meal".
You tried negatine "wine", you should negate "being a meal".