Cook bacon in large saucepan over medium heat until crisp. Remove bacon from saucepan, reserving drippings; drain bacon on paper towels. Set aside.
To bacon drippings in saucepan, add potatoes, celery, onion, salt, thyme, pepper and reserved clam liquid. Bring to a boil. Reduce heat; cover and simmer 10 minutes or until vegetables are crisp-tender.
In 1-quart jar with tight-fitting lid or medium bowl, combine flour and milk; shake or stir with wire whisk until smooth. Gradually stir into vegetable mixture. Cook over medium heat for about 15 minutes or until thickened, stirring frequently.
Stir in clams. Reduce heat to low; cook and stir until thoroughly heated. DO NOT BOIL. Top individual servings with bacon.