The ornamental design for a bezel for a lightbar, as shown and described.
FIG. 1 is a perspective environmental view of a bezel for a light bar showing our design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a top plan view thereof, the bottom plan view being a mirror image thereof; and,
FIG. 5 is a left elevational view thereof, the right elevational view being a mirror image thereof.
The broken lines shown in the drawings are for illustrative purposes and illustrate portions of the bezel for a light bar that form no part of the claimed design. Where applicable, the use of separation and bracket indicate that, for ease of illustration, the precise width or height of the design is not claimed.