A ship named "The City of Dublin" 1824 - 1840 sailed between Dublin and Liverpool.
See link:
http://www.theshipslist.com/ships/lines/cityofdublin.shtml I also found a William Clark (Clarke) born 02- Jul - 1821 in Dublin to William Clarke and Mary Flanagan they also had three other children born in Dublin James born in 1825, Elizabeth born in 1827 and Eliza born in 1834.
Tim