Just a square wave synth. I can't think of anything simpler than this.
Drums. There's a looped 1/4 note sample, I hear a typical vinyl kick and some sort of percussion on the offbeat, sounds like a woodblock/cowbell. At the end of the track you can hear second kick layered with kick from a sample.
And yeah, a reverbed digital clap on top of it all.
I feel like the bass is driving the track mainly.