I think you mean combination item.

Do you mean:
"For dinner, I ate steak, macaroni and cheese,(COMMA) and green beans."

The commas group the ideas into single items, and two item combined that represent a culinary dish.

"For breakfast, I had cereal, bangers and mash,(COMMA) and toast."

OK, combination item. Your suggestion would work if we used the oxford comma here, in my organization it is not typically used.