Heat oil in large pot or Dutch oven on medium. Add celery, onion and carrot and cook, covered, stirring occasionally, until tender, 8 to 10 minutes. Stir in garlic and red pepper flakes and cook 1 minute.
Add potatoes, thyme, clam juice, tomatoes and their juices (crushing tomatoes as you add), white wine, and ½ cup water and bring to a boil. Reduce heat and simmer until potatoes are tender, 8 to 10 minutes. Stir in clams to heat through.
Sprinkle with parsley and serve with bread if desired.
