Put the fully cooked ham into a slow cooker that is at least 6 quarts in size.
Whisk together the brown sugar, honey, Dijon mustard, ground clove, and ground cinnamon in a small bowl and then pour the mixture evenly over the ham.
Cover the slow cooker with its lid and cook the ham on the LOW setting for between 4 to 6 hours, or choose HIGH and cook for 2 to 4 hours; continue until the internal temperature hits 140°F (60°C).
Carefully remove the ham from the slow cooker and loosely cover it, letting it rest for a few minutes.
Meanwhile, pour the cooking juices into a saucepan and heat it until it simmers gently.
Stir a small amount of cornstarch mixed with water into the simmering juices gradually, whisking continuously until the sauce thickens to your liking.
Brush the thickened glaze over the cut slices of ham and serve, enjoying the extra flavorful coating.