The ornamental design for a rearcombinationlamp for an automobile, as shown and described.
FIG. 1 is a perspective view of a rear combination lamp for an automobile showing my new design;
FIG. 2 is a another perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a top plan view thereof; and,
FIG. 5 is a left side elevation view thereof.
The de-emphasized and halftone portions shown in the drawings illustrate environmental structure for a rear combination lamp of an automobile that form no part of the claimed design.