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 pair of horizontal evenly spaced dashed lines represents an actual depiction of a portion of the claimed design. The uneven broken line showing of the window and the display screen is for illustrative purposes only and forms no part of the claimed design.