Mix wine, garlic, oil, rosemary, thyme, and allspice in large resealable plastic bag. Add pork and turn to coat. Marinate at least 30 minutes and up to 1 hour, turning bag occasionally.
Preheat oven to 375°F. Remove pork from marinade and place on rack on rimmed baking sheet; discard marinade. Spread 3 tablespoons mustard all over pork. Roast until thermometer inserted into thickest part of pork registers 145°F, about 25 minutes. Transfer pork to platter and let stand 10 minutes.
Meanwhile, boil cream, broth, tarragon, and remaining 2 tablespoons mustard in heavy medium saucepan until reduced to 1 cup, whisking occasionally, about 10 minutes. Season sauce to taste with pepper.
Slice pork crosswise into rounds and serve with sauce.
