If Alexander married in Ireland in 1814 and did not migrate to Britain until after 1841, then he should appear in the Tithe Applotment Books of whichever Irish parish he lived in.
There is no Dann in county Clare in the index to the TAB transcriptions at
http://www.clarelibrary.ie/eolas/coclare/genealogy/tithe_applot/name_index/index12_D%27EsterreToDigidan.htmI believe that the surnames Dann and Dunn(e) are similar in pronunciation and may be interchangeable.
There are only a handful of Dunn(e)s in the Clare Tithes and none is called Alexander.
So my guess is that you should be looking in some other county; according to
http://irish-genealogy-news.blogspot.com/2011/01/happy-new-year.htmlon 1 Jan 2011: "The Tithe Applotment Books are being transcribed by the LDS church and, when completed, will be uploaded for free access onto the Family Search website."
According to
http://brew.clients.ch/MLBonds.htm"LDS film no.149 ... shows the notes of Philip Gossle, dating from 1921-22, listing Marriage License Bonds for Killaloe ... for the period 1772-1868."
You might want to check that film to confirm whether it is the source of the submission to the IGI and to see if it includes further details of either party.
You might also want to read the related discussion over at
http://www.ourlibrary.ca/phpbb2/viewtopic.php?f=1&t=450about another person whose ancestors appear in the Killaloe DIOCESE MLBs but who is (wrongly!) being claimed for Killaoe TOWN by the local press.
According to Grenham, the Church of Ireland parish registers for Killaloe PARISH back to the late 1600s are on microfilm in the National Archives of Ireland; according to Ryan, the surviving Catholic registers for the parish do not begin until 1828.