Make a blonde roux to salvage gumbo that separated?

If you just want to thicken it, just use some cornstarch mixed with a bit of water and stir that in the pot as it boils. When the gumbo is hot and you add the cornstarch mix, it tends to thicken better than adding to a cool/cold pot.

Start off with a couple tablespoons of cornstarch and 1/4 cup water mixture and see how that goes.

I had this problem for the first time a few weeks ago. I scoured the internet and all of the suggestions failed for me. I remembered reading about an oilless roux on John Folse's website. You basically just brown the flour without any oil until you get your desired color. His directions call for doing it in the oven but I was in a rush and only needed a little. So, I did it on the stovetop and just kept stirring until it browned a bit. I then added that in a little at a time and mixed until the roux in the gumbo came together again and I got the consistency I wanted.