Grind 1 tsp. rosemary with garlic with a mortar and pestle to make a paste, then stir in 1/2 tsp. oil. Pat venison dry and put in a bowl, then rub with paste.
Season well with pepper, then cover and chill 20 minutes.
Preheat bbq or oven to 450˚F.
Spray your grill very well with PAM or other grilling spray.
Season venison well with salt, then roast on grill, turning once, about 6 minutes total. Transfer the meat to the indirect side of the grill, away from direct heat, and roast the venison until an instant read thermometer inserted diagonally into center registers 125 degrees F, 7 to 10 minutes.
Transfer the meat to a plate and cover tightly with foil. Add wine and cherries to a skillet and boil over moderately high heat, stirring continuously.
Stir together broth, water, cornstarch, and remaining 1/2 tsp. rosemary in a bowl and add to skillet. Simmer, stirring, until thickened, about 5 minutes. Whisk in jelly and salt and pepper to taste.
Cut venison into 1/4inch thick slices and serve with the sauce. Venison should be medium rare inside.