Place flour in a 9-inch cast-iron skillet; cook over medium heat 20 minutes or until browned, stirring constantly with a whisk. (If flour browns too fast, remove it from heat, and stir until it cools down.) Remove from heat; set aside.
Heat oil in a large Dutch oven over medium heat. Add onion, bell pepper, celery, and garlic; sauté 8 minutes or until vegetables are tender. Add okra and tomato; cover and cook 5 minutes, stirring occasionally. Add 1 1/2 cups water, Cajun-Creole Seasoning, clam juice, and bay leaves, and bring to a boil. Gradually add browned flour, stirring with a whisk. Reduce heat; simmer, uncovered, for 45 minutes, stirring occasionally.
Add snapper; cook 5 minutes. Add green onions, crayfish, and shrimp; cook 10 minutes or until seafood is done. Stir in hot sauce; discard bay leaves. Serve gumbo over rice.
Note: One (8-ounce) container select oysters, undrained, can be substituted for crayfish, if desired.