Sauté onion and celery in butter and olive oil in a large Dutch oven over medium heat 4 minutes or until tender. Add wine and next 3 ingredients; cook 5 minutes or until mixture is reduced by half, stirring occasionally.
Stir in broth and meatballs. Cover and bring to a boil; reduce heat, and simmer 10 minutes. Add orzo and clams; simmer 10 minutes or until orzo is tender and clams have opened. Discard any that do not. Stir in parsley, 1/4 cup cheese, and lemon juice.
Ladle soup into bowls. Serve with additional cheese.
Quick tip The next time you make meatballs, double the recipe and keep a batch on hand in the freezer. Or, to keep it simple, buy prepared frozen meatballs; try Farm Rich--the party size works well for soups.
Recipes reprinted with permission from 300 Sensational Soups (Robert Rose, 2008) by Carla Snyder and Meredith Deeds.