Is there a way to make a specific color transparent?

I'm trying to make a brief animation using a gif that doesn't have a transparent background. It's background is a solid color though. I've tried opening it in Photoshop and using "remove background" on it, but that messes with the image, and when I import the finished product into Animate, the last two frames of the animation display at the same time, even though the resulting gif plays normally when I open it outside Animate, but exporting the mess out of Animate DOES export the erroneous double layer... SO I'm trying to go what I personally think is the simple route. Is there a way that I can simply tell Animate "make anything that is white transparent?" Some kind of transparency mask that just makes it transparent if it's white?