Attachment for Grooming Device

FIG. 1 is a front, top, and right side perspective view of an ornamental design for an attachment for a grooming device; FIG. 2 is a top plan view thereof; FIG. 3 is a bottom plan view thereof; FIG. 4 is a left side elevation view thereof; FIG. 5 is a right side elevation view thereof; FIG. 6 is a front side elevational view thereof; and, FIG. 7 is a rear side elevational view thereof. The dashed broken lines in the Figures show portions of the attachment for a grooming device that form no part of the claimed design.