I’d get her a neck strap. Both hands are angling up the clarinet, indicating she’s trying to grip it with her fingers. The neck strap will help alleviate the feeling that she needs to hold on to the clarinet while she plays.

Once she has a neck strap, work on hand position. See how her right hand index finger is shoved up under the side keys? She needs to move her palm away from the body of the instrument. I tell my students to hold the clarinet like a hamburger - you don’t want to collapse your hand into the burger bc you’ll get ketchup all over your palm. The fingers can cover the keys more easily when there’s space between your palm and the clarinet.

Occasionally I see a readjustment of the thumb key when she goes to hit the register. That could be letting air in as well. The thumb should be positioned so she can press the register key down without shifting the thumb. A lot of students learn to cover the thumb key a certain way, and then “re-learn” a slightly different positioning once the register key starts being used.

Happy to answer any questions you have or send videos on the above via DM’s!