The ornamental design for a filter for a wet/dry vacuum cleaner, as shown and described.
FIG. 1 is a bottom perspective view of a filter for a wet/dry vacuum cleaner showing our new design;
FIG. 2 is a bottom view thereof;
FIG. 3 is a side view thereof;
FIG. 4 is a side view thereof, showing the side as rotated 90° from that shown in FIG. 3;
FIG. 5 is a top view thereof; and,
FIG. 6 is a top perspective view thereof.
The broken line showing of details in FIG. 5 is included for the purpose of showing environmental portions of the filter for a wet/dry vacuum cleaner and forms no part of the claimed design.