The ornamental design for a support for a pressurewasher, as shown and described.
FIG. 1 is a front perspective view of a support for a pressure washer showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a left side view thereof, the right side view being a mirror image;
FIG. 4 is a rear view thereof;
FIG. 5 is a top end view thereof;
FIG. 6 is a bottom end view thereof; and,
FIG. 7 is a front perspective view showing environment.
Portions of the support for a pressure washer and the pressure washer shown in broken lines are for environmental purposes only and do not form part of the claimed design.