The ornamental design for a belt, as shown and described.
FIG. 1 is a perspective view showing the new design for a belt;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines showing portions of a belt are included for the purpose of illustrating environmental structure, and form no part of the claimed design. Any shading is provided to illustrate contour only and is not an indication of texture, gloss, etc. The dash-dot-dash lines represent a boundary to the claimed portion of the design, and form no part of the claimed design.