The ornamental design for a tag for footwear, as shown and described.
FIG. 1 is a top front right perspective view of a tag for footwear, showing my new design;
FIG. 2 is a bottom rear right perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a right side elevation view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The portions in the figures which are shown in broken lines are intended to show the environment in which the tag for footwear is used and do not form a part of the claimed design.