The ornamental design for a portion of a lightingfixture, as shown and described.
FIG. 1 is a bottom perspective view of a portion of a portion of a lighting fixture showing my new design;
FIG. 2 is a top perspective view thereof;
FIG. 3 is an enlarged bottom plan view thereof;
FIG. 4 is an enlarged top plan view thereof;
FIG. 5 is an enlarged side elevational view thereof, the other side being a mirror image; and,
FIG. 6 is an enlarged end elevational view thereof, the other end being a mirror image.
FIGS. 1–5 are broken away to indicate indeterminate length. The broken lines are shown in FIGS. 1 and 2 for illustrative purposes only and form no part of my claimed design.