To help kill plants, you need to spray them while they're active..... Fertilizing a few days or a week before spraying helps. Same goes for adding lime.
Spraying a day or so before a good rain helps, or right after one, once the leaves dry out of course.
Adding ammonium sulfate to a tank of gly helps too. Not only it's a quick acting fertilizer, it also opens up defenses of certain weed cell walls.
Not totally perfect, but a combination of gly and 2,4D is considered to kill pretty much anything.
Mowing during a dry speel or spraying a light dose of gly can set back clover.