While the turkey is roasting place the giblets, turkey neck and clipped turkey wing tips into a large saucepan with the carrots, celery, water and chicken stock. Bring to a boil over medium heat, skim off any foam that forms on the top, reduce heat to low and simmer the stock for 3 hours. Strain the stock, skim off the fat and set aside. There should be about 4 cups of stock.
Skim off and discard all but 1/4 cup of the fat from the drippings in the roasting pan and place the roasting pan over medium heat. Whisk in the flour then cook and stir the flour mixture until it becomes pale golden brown, about 5 minutes.
Whisk in the stock and tomato paste; bring to a boil, simmer for 5 minutes then whisk in the jam. Simmer for 10 more minutes. Season to taste with salt and black pepper.