The sources I found on the geni.com page for Robert Clements' wife are (1) a link to her wikitree page (which states that there is no support for her maiden name being Drummer), (2) broken links to ancestry.com trees and (3) links to unsourced family trees. I also found no mention on her geni.com page of her having been married before Robert Clements (whether to a Drummer or anyone else).
She was a widow of Robert Drummer when she married 2nd to Rev Robert Clements. There is plenty of Documentation
Unfortunately this positing site does not accept cut and paste .Rev Robert Clements Sr so check for links ROBERT DRUMMER
"There is plenty of Documentation" - There are lots of unsourced websites and family trees that say she was a Drummer, but I none that I've seen (including geni.com) cite any reliable source or provide any reliable evidence to support that claim. I would love to find some, so if you have any, please provide a citation or link.
The geni.com profile for Robert Drummer has no sources. I don't see any sources on the geni.com profile for Rev Robert Clements for his wife's surname before marriage being Drummer -- lots of statements that she is, but no sources.