Well, with just ‘Nena’ and ‘Tiffany’ it might not be female one-hit wonders… you really need at least three to establish a trend…

What’s the name of Claire’s? If it needs renaming to fit in, here are some suggestions:

Sylvia
Claire
Nicole
Sabrina
Dominique (Song, not singer, but she is female so it kind of counts)

That’s all the ones I can think of who recorded under a single-name title..