A white child of the upper classes is left behind (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

definition: a white wine I think the wordplay is: CH (child) + A and B + IS behind L (left) …but not sure about "is left behind" giving IS after L A and B are used in a variety of contexts to denote the first or top two classes/tiers/grades/categories, so "upper classes"