Remove giblets and neck from duckling; reserve for other uses. Rinse duckling thoroughly with cold water; pat dry. Prick fatty areas of duckling with a fork at intervals. (Do not prick breast.) Fill cavity of duckling with 3/4 cup currant jelly. Close cavity with skewers; truss. Lift wingtips up and over back, tucking under bird securely. Fold neck skin under, and place duckling, breast side up, in a shallow roasting pan. Sprinkle flour over duckling, and pour water into roasting pan.
Bake at 300° for 1 1/2 hours. Combine remaining jelly and wine, mixing well. Pour wine mixture over duckling; bake 1 1/2 hours or until drumsticks and thighs are easy to move. Baste frequently with pan drippings.