Score a diamond cut into ham. Combine orange juice, Grand Marnier and mustard in a bowl and combine. Pour over ham, set in a roasting pan. Poke cloves in corners of diamonds. Pack brown sugar on top of ham.
Cover with foil and place in 325 deg F. oven for 1 hour. Remove foil after the hour and continue cooking until golden and crusty, about 30 minutes. Let rest 10 to 15 minutes before slicing.