The ornamental design for an upper for an article of footwear, as shown and described.
FIG. 1 is a rearview in perspective of an upper for an article of footwear showing my new design;
FIG. 2 is a lateral side view thereof;
FIG. 3 is a medial side view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a front view thereof; and,
FIG. 7 is a rear view thereof.
The upper for an article of footwear illustrated in the drawings is a first embodiment showing a right-footed form of the upper for an article of footwear. A second embodiment is for the left-footed form of the upper for an article of footwear, which is a mirror image of the right-footed form, is not illustrated. The broken line illustration in the drawings forms no part of the claimed design. The dot dash line illustration in the drawings defines a boundary around the claimed design and also forms no part of the claimed design.