Monster in Greek mythology with the head of a bull and the body of a man (8)
I believe the answer is:
minotaur
(Other definitions for minotaur that I've seen before include "awful beast" , "Monster in a maze with the head of a bull and the body of a man" , "Am in rout of a fabulous monster" , "Mythological man-bull" , "Monster, half bull and half man, slain by Theseus in Cretan labyrinth" .)