The 46-year old Clancy had a breathing apparatus over his mouth when he was placed in the ambulance just prior to the end of practice.
This is Clancy's first season with the Oakland Raiders after coaching the Saints' defensive line the past four years.
He played 11 pro seasons as a defensive lineman. He was selected by Seattle in the 11th round in 1982. After two years with the Seahawks, Clancy played two seasons in the USFL before returning to the NFL with Cleveland and Indianapolis.