Add the bacon to a large stockpot or braiser over medium heat. When the bacon starts to render add the onions and peppers, cooking until the onions have softened and the bacon has rendered all of it’s fat.
With a slotted spoon remove the bacon and vegetables, setting aside. You want about 1/3 cup of bacon fat still in the pan (no need to meticulously measure, just eyeball it), if there is significantly more than 1/3 cup discard excess, if there is less add the olive oil to the bacon fat. Sprinkle with flour.
Cook the flour, stirring frequently over medium heat, until the roux is dark brown. This will take at least 20 minutes and up to 40 minutes, it’s the backbone of the dishes’ flavor so don’t skip it.
Once the roux is a dark brown add the beer, scraping to deglaze the bottom of the pan.
Add the broth, tomatoes, okra, bacon and vegetables, Cajun seasoning, cayenne, file, and sausage. Simmer until slightly thickened, about 10 minutes.
Add the shrimp and clams, stir slightly and then cover immediately. Allow to simmer for 5 minutes. Lift the lid, discard any clams that did not open. Sprinkle with parsley before serving.