The ornamental design for a taillight for a vehicle, as shown and described.
FIG. 1 is a front side elevation view of a taillight for a vehicle;
FIG. 2 is an elevation view of the taillight, as viewed from a location between the front and left sides of the taillight;
FIG. 3 is a top plan view of the taillight; and,
FIG. 4 is a left side elevation of the taillight.
The figures of the drawing depict a left-hand taillight; the right-hand taillight being a substantial mirror image of the illustrated left-hand taillight.
The broken line showing of the taillight is for the purpose of illustration and forms no part of the claimed design.