Beat the tar out of, 4 letters
Clobber with a stick, 4 letters
Thrash with a stick, 4 letters
Thrash, on the sports page, 4 letters
Wipe the floor with, so to speak, 4 letters
Defeated decisively, 7 letters
Beat thoroughly in a competition or fight, 8 letters
The act of inflicting corporal punishment with repeated blows, 8 letters