Heat the olive oil in a large pot over medium-high heat. Add the sausage and cook, turning, until browned, about 4 minutes. Add the onion, garlic and red pepper flakes and cook until the onion is soft, about 3 minutes.
Stir in the orange juice concentrate, kale and 3 cups water. Add the tomatoes and break them into chunks with a spoon. Bring to a boil, then reduce the heat to medium low and simmer until thickened, about 30 minutes.
Add the beans and clams. Return to a boil over high heat, cover and cook until the clams open, 10 to 12 minutes. Stir in the vinegar and serve with bread.