That clamp idea works for glue bottles as well.

When wanting to make a 90 degree cut to a piece of wood, I get a block that has a 90 degree angle and put it against the fence. Then I clamp or grip the piece tightly against the wood block as I run it through the saw blade. I get a perfectly clean cut.

If I need to trim the wood to a specific dimension, I adjust the fence to the approximate spot, then use cardboard shims to trim it successively until it's the correct size.

I like this better than using a miter gauge, since this gets out of whack and also because the piece can slide during its run through the saw. You do have to be careful with your hands using my method.

Click here to view attached image.

Great tip, thanks Inlver

Cutting a piece of wood that size (ratio) on a table saw with that method is asking for trouble! No matter how many times you've done it and never had a problem. If it shifts at all, it will bind between the fence and the blade and then fly back at you. Sometimes with serious consequences.
As a professional woodworker I would NEVER recommend that method.
If the piece was 3x as long as the width you're cutting it would be ok.
One good thing about the photo is your saw blade is only slightly higher than the piece of wood which makes cutting a finger off less likely.