Combine 1/2c flour, salt & pepper and rub all surfaces of the meat.
Heat oil in a heavy Dutch oven or very large, deep skillet (with cover) over medium to med-high heat. Gently brown roast on all sides. Add broth, wine, vinegar, cranberry sauce, carrots, onion, orange, celery, cloves, garlic, bay leaf, cinnamon, and thyme;. cover and simmer for approx 3 1/2hrs, or until tender.
For gravy: Measure out 4c pot roast broth (strained, if desired) from the pot or skillet; adding water if necessary. Melt butter in heavy saucepan over medium heat; whisk in remaining 1/4c flour; cook for 1 minute, then add pot roast broth gradually, whisking often to be sure it's free of lumps. Cook until thickened; season with salt & pepper to taste.
Discard orange pieces; serve pot roast with gravy & vegetables.