Preheat your oven to 325°F (165°C). Place the ham in a roasting pan, cut side down.
In a medium saucepan over medium heat, combine the brown sugar, dark rum, Dijon mustard, apple cider vinegar, ground cinnamon, ground cloves, black pepper, and salt. Stir until the sugar is dissolved and the mixture is smooth, about 5 minutes.
Pour the rum glaze over the ham, making sure to coat it evenly. Add water to the bottom of the roasting pan to keep the ham moist during cooking.
Cover the ham loosely with aluminum foil and bake in the preheated oven for 1.5 to 2 hours, basting every 30 minutes with the glaze from the pan.
Remove the foil during the last 30 minutes of baking to allow the glaze to caramelize and form a nice crust.
Once the ham reaches an internal temperature of 140°F (60°C), remove it from the oven and let it rest for 15 minutes before slicing.