The Collaborative International Dictionary
To show the cloven hoof
Cloven \Clo"ven\ (kl[=o]"v'n), p. p. & a. from Cleave, v. t.
To show the cloven foot or To show the cloven hoof, to reveal a devilish character, or betray an evil purpose, notwithstanding disguises, -- Satan being represented dramatically and symbolically as having cloven hoofs.