I claim the ornamental design for a sconce, as shown and described.
FIG. 1 is a front perspective view of a sconce showing my new design;
FIG. 2 is a rear perspective view of FIG. 1;
FIG. 3 is a front elevational view of FIG. 1;
FIG. 4 is a rear elevational view of FIG. 1;
FIG. 5 is a left side elevational view of FIG. 1;
FIG. 6 is a right side elevational view of FIG. 1;
FIG. 7 is a top plan view of FIG. 1; and,
FIG. 8 is a bottom plan view of FIG. 1.
The break lines shown in the drawings indicate that the appearance of any portion of the article between the break lines forms no part of the claimed design; and the broken lines shown in the drawings are included for the purpose of illustrating elements of the sconce that form no part of the claimed design.