Nash's first pastoral assignment was as chaplain of the vocational school in Roscrea, and as priest responsible for the local youth centre. After five years, he was appointed as general manager of Clarecare, a non-profit enterprise which provides a range of social services to people in County Clare, a position he held until 2003. Nash was also appointed curate in Corofin in 1996, before being appointed resident priest in 2003, as part of the first grouping of parishes in the Diocese of Killaloe. He remained as resident priest in the newly created Imeall Bóirne pastoral area when he moved to Crusheen in 2007.[1][3]
Nash was appointed as Diocesan Secretary in 2010, while continuing his ministry in Imeall Bóirne. He was appointed episcopal vicar for pastoral development for the diocese in 2016.[5][6]