A lot of Irish references say MacClave is a variation of Mac Flaitheamh or Mac Laithimh (These are both pronounced MacClave. In the North of Ireland Mac Flaitheamh is rendered as MacClave and in the south it is rendered as Claffey or MacClaffey. Anotehr variation is MacLevy.

It is just as possible that MacClive is a variation of this name as it is that it is a variation of Dunnshleibhe (Dunlevy, MacLeave, Livingston, MacLeay).

http://www.ancestry.ca/name-origin?surname=mcclave

http://archiver.rootsweb.ancestry.co...-11/0974169725

Based on phone books and Facebook searching, I think the biggest pocket of MacClives on earth is actually in Michigan. There are also some in West Africa which may provide a clue.