 Clery spent his last years in solitude, having never married.He was one of the lawyers who advised Éamon de Valera that the Irish Free State was not legally obliged to pay the Land Annuities which had been agreed in the Anglo-Irish Treaty of 1922.Clery was a close friend of Tom Kettle (who died serving on active duty in Europe during World War I), with whom he founded a dining club, the "Cui Bono".