Cerberus as the three headed _____ at the gate to the underworld?

I am doing a crossword. that's what it ask for. I tought it was be hound or creature or dog but it's 8 letters long. And the 2nd letter is a, the 5th letter is z and the 7th is o. I am not sure if those letter are right since i don't know if the other words that are filled in right or not. Anyone know?