Around here if you dont finish it you are served it again later, if it is wasted it is deducted from extra chore money.
Understand we don't do allowances for chores, chores are a natural result of living we all have them.
However spending money is earned by doing things we would pay for i.e. cleaning and vacuuming the car. Shoveling the walkways. Washing the windows on the outside. Things that fall into the I would rather not do them and will pay you to if you want the money.

Wasted food, lost Yu-gi -ohs, breaking another siblings toy etc is deducted from the wages and the final result of wages is what is paid at the end of the week.

works for us, maybe you can tweak it a bit to make it more suitable for your family.