The ornamental design for a clock, as shown and described.
FIG. 1 is a front elevational view of my novel clock design having a basic
octagonal shape with a geometric design in combination with a feather
design therebelow, showing the herringbone pattern and showing parallel
stitching, as indicated by the parallel lines, in the feather design as
well as at the edges of the octagonal shape;
FIG. 2 is a side view showing the parallel stitching;
FIG. 3 is a bottom view showing the parallel stitching; and,
FIG. 4 is a rear view showing an opening for insertion of a battery.