You can put lime down, it will only help - but 6.0ph should grow a nice clover plot "as is". Generally you will need about 1000 lbs per 1/2 acre to raise the PH 1/2 point. (more on clay soils).

Remeber that a point in PH means alot (10x). A Ph of 6.5 is 10 times less acidic than 5.5 ph - so it generally takes a decent amount of lime to have any effect.