The answer to this depends on the hobby itself. Most hobbies can qualify as extracurricular activities, especially when you practice them in an organized way or as part of a club or a team. For your hobby to qualify as an extracurricular, you should show that you do it regularly. If you’ve practiced, say, singing once, you can’t list “singing” or “solo music” as an extracurricular activity. However, if you’ve sand for your school’s choir more than once over a long period of time, then your music hobby can qualify as an extracurricular activity.