The ornamental design for a rearfender for an automobile, as shown and described.
FIG. 1 is a front, perspective view of a rear fender for an automobile of our new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a right side elevational view thereof, the left side elevational view being a mirror image thereof;
FIG. 5 is a front elevational view thereof; and,
FIG. 6 is a rear elevational view thereof.
The claimed design is the dark portion of the automobile depicted, the light portion forms no part of the claimed design. The back of the fender is not visible during ordinary use and forms no part of the claimed design. The claimed design includes the mirror image of the embodiment depicted that is not shown.