FYI - I was a clarinet performance major at UCLA, went to law school, and am now a political consultant/lobbyist who also plays in several great groups and even records for a few classical record labels on occasion. It can definitely be done! Double majors are also a possibility. But yes, you need to audition now. The experience you get in college with a private instructor and in playing with orchestral groups and chamber ensembles, as well as having juries and junior/senior recitals will be critical to your musical growth.