If that is the scenario you are afraid of I highly recommend getting a small fixed blade and learning how to use it. Some of the best for this range are the Fred Perrin La Griffe and Le Shark designs, or the Brous Blades silent soldier. These have rings in the handle which allows for a positive grip on draw and makes it very hard for you to be disarmed. They are neck knives but can easily be worn on the belt either inside or outside waistband. The Spyderco Street Beat is another great option but they only have the lightweight version available right now which comes with a terrible sheath that dulls the edge.
Perrins are the small silver blades on left, small ringed knife on right are Brous Silent Soldiers. All knives perfect for your described scenario. Knives in the middle are not good for self defense.
Included here are Perrin Street Beat and shivworks clinch pick. Clinch pick requires some extra training and understanding to use its edge in methodology. However it is literally made for clinch range.
Benchmade SOCP dagger is another great option. Comes with a very obtuse edge and no slashing ability. It is a stabbing knife for “get off me” encounters. They have a single edged version.
If you insist on carrying a folder then the only viable way I see which still isn’t as good as a fixed blade is to have a waved folder set up for reverse wave and to practice waving until it becomes second nature. Practice waving sitting down, laying on your back and standing on your head. You have to set it up for reverse wave because the regular wave puts the knife in a grip that is not secure when you draw the knife. With reverse wave draw you can just close your fist and the knife will be secure. Imho the best up close fighting waved folders are the Spyderco Pikal or waved delica or endura. Pikal needs some of that Shivworks training and understanding to take advantage of its edge in grip.
Spyderco Pikal. A folding version of the clinch pick. This knife was designed for exactly the type of self defense scenario you are describing. Reverse waving then closing your fist around the handle will put a knife into revrse grip edge in. In my estimation this is the only way to draw a folder fast and securely enough for self defense. The only other option is ringed folders like the karambit.
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Me reverse waving my Spyderco Pikal from my left pocket. Grip is modified to show the camera what’s happening.
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Wavee Endura and Delica. Great SD / utility options.
Put a WiseMen Signet Ring on these to turn them into even truer viable self defense folders.