Extracting the talking (lyrics) from an audio in python
What you are trying to do might be extremely difficult depending on numerous factors. I have read about a technology called blind source de-convolution which tries to separate one audio source from others. In the end rather than recovering every audio source you will most likely recover only the one you are interested in.

I would suggest you start with this survey article which lists many of the attempts that have been done to achieve blind source de-convolution.

If what your are trying to do doesn't have to be too precise, as a very simple start you might just want to filter every frequency component above 4-5 kHz because the main energy of human voice is below that. However if it is a song with a strong bass, for instance hip-hop, pop, drums, etc, this won't help you clean that