Wash chicken and giblets and pat dry. Season with salt and pepper and saute in butter. Transfer to crockpot. Rinse out drippings with water and pour into crockpot. Place carrots, parsnips, celery and leek around chicken. Season vegetables with salt and pepper. Add garlic, oregano, broth and wine. Cover pot. Cook on low for 8 hours or until tender. Remove chicken and vegetables to a platter and keep warm. Pour pan juices into saucepan. Skim fat. Boil down until reduced to 1 cup.