CLAIM The ornamental design for a user interface for a portion of a display screen, as shown and described.
Description:
The FIGURE is a front view of a user interface for a portion of a display screen showing my new design.
The broken line showing of the rectangles and squares within the user interface and the unshaded areas within them form no part of the claimed design. The broken line showing of the portion of a display screen is for illustrative purposes only and forms no part of the claimed design.