The ornamental design for buckle for footwear, as shown and described.
FIG. 1 is a front perspective view of a shoe showing my new buckle design;
FIG. 2 is a right side view of the buckle for footwear shown in FIG. 1;
FIG. 3 is a left side view of the buckle for footwear shown in FIG. 1;
FIG. 4 is a front view of the buckle for footwear shown in FIG. 1;
FIG. 5 is a rear view of the buckle for footwear shown in FIG. 1; and,
FIG. 6 is a top view of the buckle for footwear shown in FIG. 1.
The broken line showing of the sole, heel, heel cap, footbed, and portions of the shoe upper in the relevant drawings shows unclaimed subject matter for the design in those drawings.