The ornamental design for a levelsupportclamp, as shown and described.
FIG. 1 is a front perspective view of a level support clamp showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left side view thereof, a view from the right side being a mirror image;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is an illustrational view thereof in use.
The broken line showing of parts of the drawings is included for the purpose of illustrating use and environment and forms no part of the claimed design.