clean (one's) plate (up)
To eat all of the food that is on one's plate. He's usually a really picky eater, so I'm shocked that he cleaned his plate! You'll have to clean your plate up if you want dessert.
clean (up) one's plate
to eat all the food on one's plate. You have to clean up your plate before you can leave the table. Mom said we can't watch TV tonight unless we clean our plates.