As a seventeen-year-old Smyth made his senior debut in a National Hurling League game against Galway in 1948. He played no part in the subsequent 1949 championship due to his involvement as captain with the Clare junior hurling team. He won a Munster medal in that grade following a 3–3 to 0–6 defeat of Cork. Clare later defeated Kilkenny before facing London in the All-Ireland decider. A close game developed and, at the full-time whistle, Clare were narrowly defeated by 3–7 to 3–6.