Of course, it's very risky to try to say anything good about a slaveholder. But if you accept the premise that the Civil War was better being fought in 1860 than in 1825, Clay does deserve some credit. Without the Missouri Compromise, the southern states likely would have seceded much earlier. And it was the overturning of the Missouri Compromise in 1856 ( along with the Dred Scott case) that started the descent into war.

A good politician could be defined as someone who settles things when there are seven people to share a pie and each one feels entitled to a third of it. Clay is an outstanding example of a good politician.