@Ryan R voltage sources are ideal devices. Internal resistance is 0. If vclamp is set to 0V then there is no voltage across M11 and all current goes to VCLAMP. If VCLAMP is low, less than M11 threshold, then most current will go thru VCLAMP as M11 is off. If you set VCLAMP to a voltage that is bigger than M11 Vth (M11 will be conducting) then some current will flow into M11. Usually a clamp is done by setting VCLAMP to some voltage and putting a diode such that if M11 drain goes above

VCLAMP + diode threshold

then excess current will go thru the clamp voltage source.