Sarah:
Welcome to Ireland Reaching Out!
I don't think the record is avauilable. The Clara/Horseleap marriage records go back to 1821 according to the Roots Ireland (subscription site) data base. I did a search for all of Ireland for a Joseph Walsh marriage to a Conway and no records come up. So likely they were married in a parish that does not have records back to 1827 and earlier.
Roger McDonnell