FIG. 1 is a top front perspective view of my new, original and ornamental design for a clamping level tool; FIG. 2 is a front elevation view thereof, the rear elevation view being a mirror image thereof; FIG. 3 is a top plan view thereof. FIG. 4 is a bottom plan view thereof; FIG. 5 is a front end view thereof; and, FIG. 6 is a rear end view thereof. The broken lines are for illustrative purposes only and form no part of the claimed design