The ornamental design for a portion of a shoe upper, as shown and described.
FIG. 1 is a front perspective view of a portion of a shoe upper showing my new design;
FIG. 2 is a rear perspective view thereof; and,
FIG. 3 is a side view thereof.
The uneven broken line immediately adjacent to the shaded area represents an unclaimed boundary of the design. The unshaded region within the shaded region and the broken line showing of the remainder of the shoe are for illustrative purposes only and forms no part of the claimed design.