How was a shy girl able to play an instrument around her crush?

First, of course, you have to overcome your shyness. You have to build some kind of confidence in front of your crush because no matter how good you are at playing your instrument, with your shyness around, you'll get it all ruined up. That would mean turning off your crush. Second, practice. You have to master your song or whatever you're going to perform in front of your crush. Third, be ready. Be ready for whatever may happen. Like, he/she might not like it or may just turn you down after, or may even get impressed to you. So, just go on with it! Opportunities only pass you once :)