Preheat oven to 325°. Cut off the tough, leatherlike skin from ham (if it has it; some hams will not), and score the fat in a crosshatch pattern. Stud ham all over with cloves, put in a large roasting pan, and loosely tent with foil. Bake until a thermometer inserted in center of thickest part (not touching the bone) registers 135°, about 20 minutes per lb. or 2 to 2 1/2 hours total, basting occasionally with any accumulated juices.
While ham is baking, make the glaze: In a medium bowl, combine brown sugar, maple syrup, and mustard. Whisk until smooth. When ham has about 40 minutes left to bake (internal temperature will be 120° to 125°), brush generously on all sides with glaze. Continue baking until ham reaches 135° and glaze is well browned.