Keep your lawns healthy and well fertilized.
Grass, if dense enough, will prevent anything else from growing there. A problem with weed overgrowth is usually a sign of issues with your lawn’s health. A lack of nitrogen is what allows plants like clover to thrive; they don’t need soil nitrogen to exist, as they can absorb it from the air. An overly compact sod base can also lead to weeds. Yearly fertilizing, aeration, and de-thatching will help get rid of your clover problem, or even prevent one from ever starting.
Manually remove it from smaller areas before it spreads.
Clover reproduces quickly via seed and has shoots that spring horizontally across the ground, spreading itself out. If you notice clover, or any weed, popping up where you don’t want it, pull it up. The sooner you pull it up, the better your chances for controlling a potential clover problem. Just be sure to pull carefully, loosening the soil around the roots, to ensure that you get everything out, or it won’t be long before the clover has grown back from its remaining roots.
Use a broad-leaf herbicide to kill clover in larger areas.
Sometimes pulling every clover plant manually isn’t possible or practical. If you are trying to control clover in a grass lawn environment, you are lucky in that there are several herbicides available that will target the broad-leaf weeds and leave your grass to grow as it did before. Be careful when applying these chemicals, as they can kill most garden plants too, not to mention any bee that happens to be flying by.
Please Note: Broad Leaf herbicide are NOT Suited for Buffalo Turf
Ripping everything up and starting over is another option.
Sometimes the weeds win. Apply an even coat of a herbicide, till the soil, add some compost and fertilizer, and start over. It would be a lot of work, but then you would know what you are dealing with, and it would be much easier to prevent weeds in the future with basic lawn care techniques.