The ornamental design for a combinationgrip for an exercise device, as shown and described.
FIG. 1 is a perspective view of a combination grip for an exercise device according to the present invention;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left side perspective view thereof;
FIG. 5 is a right side perspective view thereof;
FIG. 6 is an enlarged top side view thereof; and,
FIG. 7 is an enlarged bottom side view thereof.
The broken lines in the figures are for the purpose of illustrating the sewing thread of the combination grip for an exercise device that form no part of the claimed design.