You don’t need a “strong” embouchure, you need a relaxed embouchure.
Embouchure “strength” is a myth. Stop biting and pinching.
Your embouchure is made up of little facial muscles, which are good at subtle, expressive movements, like for facial expressions and language (or for nuanced variations in woodwind dynamics and tone color). They aren’t good at feats of strength or endurance.
Your abdominal muscles, on the other hand, are very good at strength and endurance. You use them all day long and they probably never feel tired unless you are doing sit-ups or something. Instead of straining with your embouchure, let breath support do the work.
You should probably check on your voicing, too. I mean, you could bite your clarinet up to pitch instead, but it’s painful and causes lots of other problems.
You know that thing where you play a reed instrument and you get a blister or callus from your teeth on your lower lip? Good news, you don’t need a dental appliance or some kind of tape. You just need to relax your embouchure. Try it! Now you can practice for hours without fatigue or blood, and sound better doing it.
Ever try to play in one of the upper registers of the flute, and get an undertone or some dirtiness/growliness in your attacks? The key to clear, beautiful transitions into the upper register is a relaxed and flexible embouchure.
We can argue about whether your jaw is part of your embouchure. Nah, never mind, I have better things to do. But in any case it should be open, creating space for the soft tissues of your lip and facial muscles to make the aperture. Go ahead and unclench. By the way, opening up your jaw is what people really mean when they tell clarinetists (mostly) to do weird things with their chins.
I know, somebody taught you in your formative years about the vital importance of a brutishly muscular embouchure. Take a deep, cleansing breath. Everything is going to be fine.
