The ornamental design for a cuff, as shown and described.
FIG. 1 is a perspective view of the cuff showing the new design;
FIG. 2 is a left elevation view thereof;
FIG. 3 is a right elevation view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is a perspective view of the cuff on a wearer's leg.
The broken lines on the cuff in FIGS. 1-6 depict portions of the cuff and form no part of the claimed design. The broken lines showing a wearer's leg and foot in FIG. 6 depict environmental structure and form no part of the claimed design.