Improving sound quality?

[1LOVE-T]

There's a song I've recently downloaded that has no recorded version of it. It's the best quality I've found, but unfortunatly it's still not very..listenable quality. I was wondering if there was a way to clean up the song (maybe on audacity, which I have) by lowering the sound of the piano and increasing the sound of the voice, as well as improving clarity? Btw, this is one file, not recorded seperatly.
If anyone can help, thank you in advanced