This poor struggling vine is growing in my neighbours yard. It has just this one flower. To me, the flower looks similar to some type of clematis but it's much smaller than the usual clematis flowers and the foliage looks different to me.

Hi Christina
Sure looks like a Clematis to me! There are hundreds of different Clematis...this one looks like it could be Ville de Lyon

Looks like a Clematis to me..
But don't know which variety...

it's definitely a clematis. i can't find one that is exactly like that flower tho...