Clover is often associated with low soil fertility. Clover is a perennial weed with seeds lasting in the soil for many years and has an extensive root system. Clover is best managed with a combination of 2,4-D, MCPP and Dicamba. This combo is sold under a variety of trade names. Clover is not suseptible to 2,4D alone as are most of the other broadleaved weeds. If you want to treat this spring, wait until the young growth on your flowers has matured or wait until fall.
Fertilization should be done based on a soil test so that you can apply what is missing without putting down nutirents that are not needed, saving the enviornment and money. Turf responds to nitrogen the best of the three main nutients found in commercial fertilizers. If you want to apply, a formula similar to a 10-6-4 (NPK) will be fine. If you are only going to apply once a year, the fall is the preferred time. The soil test will also tell you if you need to add material to change the pH. Most of our soils do not need lime.