I have a Traeger Pellet smoker. Below the grill grate is a large steel plate on an angle. I cover it with aluminum foil. The drippings run down into a small bucket that hangs outside the smoker. After each smoking I change the foil and about once a year I tear the whole thing down and use a degreaser. It stays pretty clean . Before I load it, I run the temp up and brush the grill clean.
What type smoker are you using?