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;
FIG. 3 is a side elevational view thereof; and,
FIG. 4 is a top plan view thereof.
The area within the solid and dot-dash-dot lines forms the claimed design. The area within the broken lines is environmental and forms no part of the claimed design.