Lightly flour and season meat. In a roasting pan, gently saute the onion and bacon over high heat in 1 tablespoon clarified butter untill browned. Remove bacon and onion to a dish and set aside. Add the meat and brown all over. Remove. Add bacon and onion back to pan, creating a bed. Place the meat on top and reduce heat.
Stir in brown sugar. Add the water, beer (reserving 3 tablespoons), wine vinegar, bay leaf, and cloves. The liquid should cover the meat half way. Cover and simmer for 2 1/2 hours. Skim the fat from the surface and remove the cooked meat to a carving board.
In medium saute pan, lightly saute mushrooms in the remaining tablespoon of clarified butter. Add lemon juice and cayenne.
Strain the meat braising liquid and return to roasting pan, skimming any remaining fat. Bring to a boil. Mix arrowroot with reserved beer and add to pan. Cook for another minute to thicken. Add the oysters and mushrooms.
Carve meat into thick slices. Lay meat serving platter and dress liberally with sauce.