The ornamental design for an accessoryclamp, as shown and described.
FIG. 1 is a perspective view of an accessory clamp, showing our new design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a left-side view thereof
FIG. 5 is a right-side view thereof;
FIG. 6 is a front view thereof; and,
FIG. 7 is a rear view thereof.
The broken lines are for environmental purposes only and form no part of the claimed design. The shading illustrated in the figures is provided merely to represent the contour of the design and is not intended to be illustrative of the texture, gloss, or surface decoration.