I would MOW it before that grass goes to seed head, if you do that, the clover should be able to choke out the grass then, by out growing it and shading it out
IF its only 10% grass like
Grass grows FASTER than clover, that's why it can over take a clover plot fast if NOT treated
SO< when its tall enough to mow and before grass goes to seed head, MOW That sucker and you should be good!