We claim the ornamental design for a support for an exercise device, as shown and described.
FIG. 1 is a rear side perspective view of a support for an exercise device;
FIG. 2 is a front side perspective view of the support of FIG. 1;
FIG. 3 is a first side view of the support of FIG. 1;
FIG. 4 is a second opposite side view of the support of FIG. 1;
FIG. 5 is a rear view of the support of FIG. 1;
FIG. 6 is a front view of the support of FIG. 1;
FIG. 7 is a top view of the support of FIG. 1; and,
FIG. 8 is a bottom view of the support of FIG. 1.
The ornamental design that is claimed is shown in solid lines in the drawings. The broken (dashed) lines shown in the drawings are included for the purpose of illustrating environmental elements only and form no part of the claimed design.