Mix ketchup, mustard and 1/3 cup cranberry sauce in a bowl. Cover remaining cranberry sauce; refrigerate.
Mix remaining ingredients and cranberry mixture in a bowl. Form into a loaf; transfer to slow cooker. Cover. Cook on low until a thermometer inserted into center registers 180F, 6 to 8 hours.
Preheat broiler.
Transfer loaf to a foil-lined baking sheet.
Brush with reserved cranberry sauce. Broil until sauce bubbles, 30 seconds to 1 minute.