If clover is taking over your yard, it is usually a sign that you are mowing too low. Clover stays pretty low to the ground. If you keep your grass 3" or taller, it will naturally crowd out the clover (give it time).
The two best selective herbicides for clover are Dicamba and MCPP. Most general lawn weed sprays contain Dicamba.
Ortho Weed-B-Gone in the ready-to-use jug contains both, so it is more effective for clover. (Only the ready-to-use "jug" version contains both. The concentrate and hose attachment versions only contain Dicamba. No idea why.)