 Clery opposed the Anglo-Irish Treaty because he believed it would lead to re-Anglicisation and the eventual return of the Union.He was elected to Dáil Éireann as an abstentionist independent Teachta Dála (TD) for the National University of Ireland constituency at the June 1927 general election.He did not take his seat and he did not contest the September 1927 general election since new legislation obliged candidates to pledge in advance that they would take their seat.