clamp down on

:  a device designed to bind or constrict or to press two or more parts together so as to hold them firmly

:  any of various instruments or appliances having parts brought together for holding or compressing something

:  to fasten with or as if with a clamp

:  to place by decree :  impose

:  to hold tightly

:  toward or in a lower physical position

:  to a lying or sitting position

:  toward or to the ground, floor, or bottom

:  down (see ¹down) along, around, through, toward, in, into, or on

:  to cause to go or come down (see ¹down) : such as

:  to cause to fall by or as if by shooting :  bring down

:  consume

:  occupying a low position

:  lying on the ground

:  directed or going downward

:  descent, depression

:  an instance of putting down someone (such as an opponent in wrestling)

:  a complete play to advance the ball

:  an undulating usually treeless upland with sparse soil

:  a sheep of any breed originating in the downs of southern England

:  a covering of soft fluffy feathers

:  these feathers

:  something soft and fluffy like down