Galician Traditional Music. This is not a polka, it is a Galician danza (translates to "dance" in English). Very simple melody, if I’m not mistaken there is an offbeat rhythm.
I got it from the Galician band Milladoiro. They do very simple clapping accompaniment at the end of the tune and in the concerts they always invite the public to join in. I transcribed the clapping with numbers 1, 2, 3 and 4.
This is the tune in their album recorded in studio, the clapping is at the end: