I claim the ornamental design for an anchoring device, as shown and described.
FIG. 1 is a perspective view of an anchoring device with a shackle shown in a retracted position;
FIG. 2 is a perspective view thereof with the shackle shown in an upright position;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a top elevational view thereof with the shackle in the retracted position;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a left side elevational view thereof;
FIG. 7 is a right side elevational view thereof;
FIG. 8 is a left side elevational view thereof with the shackle shown in the upright position; and,
FIG. 9 is a top elevational view thereof with the shackle shown in the upright position.
The broken lines illustrate unclaimed portions and form no part of the claimed design. A bottom view is omitted as the bottom is flat and devoid of surface ornamentation.