We claim the ornamental design for a brush for cleaning a grill, as shown and described.
FIG. 1 is a front, left side, top perspective view showing our new design for a brush for cleaning a grill;
FIG. 2 is left side view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is right side view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a rear perspective view thereof.
The broken lines showing is included for the purpose of illustrating environment and forms no part of the claimed design, unless where the broken lines are elongated and intended to be claimed as stitching.