Abstract: An instrument for clamping and cutting a deformable flexible tube includes handles and jaws pivotally coupled together on opposite sides of a pivot member, a fixed cutting blade on the jaws, integrally hinged lockable V-clamps with ratcheted inner gripping surfaces mounted in the jaws with the edge of the cutting blade positioned above the ratcheted surfaces of the V-clamps, and a device to push the V-clamp axially forward in the jaws. When the handles are pressed together to an intermediate position, the jaws are closed only partially locking the arms of the V-clamps while leaving the edge of the cutting blade distanced from the center of the clamp and from the tube, and when the handles are pressed further to a cutting position, the locked V-clamp is pushed forward in the jaws simultaneously closing the jaws completely and bringing down the cutting blade.