The ornamental design for a portion of a shoe upper, as shown and described.
FIG. 1 is a rear perspective view of a shoe upper showing our new design;
FIG. 2 is a lateral side view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a medial side view thereof; and,
FIG. 5 is a top view thereof.
The even broken lines showing within the shaded area represent stitching. The dotted lines immediately adjacent to the shaded region form unclaimed boundaries of the design. The remainder of the shoe is for environmental purposes only and forms no part of the claimed design.