Thank you for your message.
Do you know what religious denomination Frederick was? This will help determine where you should be looking for his birth record.
Most Catholic records are held locally. You could try writing to the parish priest for possible assistance. One website which you may find helpful however, is the irishtimes. Here they give an overview of what records are available in specific parishes. There are two Clonmel ROman Catholic parishes: Clonmel St. Mary's and Clonmel Ss. Peter and Paul.
To see what records are available in St. Mary's follow this link:
For Ss. Peter and Paul follow this link:
For information on Church of Ireland records check: http://www.ireland.anglican.org/index.php?do=information&id=63
You could try looking for some record of George in the land records pertaining to Ireland in the 19th century. Although these do not give any genealogical information they can be used to tie a person to a specific place. There are two:
The Tithe Applotment Books, 1823-1838, found at http://titheapplotmentbooks.nationalarchives.ie/search/tab/home.jsp
and Griffith's Valuation, 1848-1864, found at http://www.askaboutireland.ie/griffith-valuation/
Some other websites which you may find helpful are:
The National Archives of Ireland http://www.nationalarchives.ie/genealogy1/genealogy-records/introduction/
The National Library of Ireland http://www.nli.ie/en/family-history-introduction.aspx
The National Archives UK ? genealogy search: http://www.nationalarchives.gov.uk/records/looking-for-person/
The Public Records Office of Northern Ireland http://www.proni.gov.uk/index/family_history.htm
Family Search: https://familysearch.org/
Genealogy Links: http://www.genealogylinks.net/uk/ireland/tipperary/index.html
I hope that this is helpful. Good luck with your research!