You can use Poast, Poast Plus or Vantage. Make sure your clover plants are a minimum of 3" tall before spraying. The most effective height to treat grass is under 12". It takes a stronger solution as the plants adds height. I try to spray at 6" and Vantage works for me.

All three products will kill the grass. The reason I chose Vantage is it comes in pints and gallons. The Poast and Poast Plus only come in 2.5 gallon containers. I don't have that much area to treat.

Remember once the grass passes 12" all three are less effective unless you mow and allow 2-3" of regrowth before you apply the herbcide.