Which clause in section 1 of the fourteenth amendment was made ineffective by an 1873 supreme court ruling?

The correct answer is the privileges and immunities clause

It was made ineffective in the so called Slaughter-house cases in which several butchers had problems with the states in which they lived. According to the supreme court cases, it was established that people have two citizenship, one of the United States federal government and one of the state in which they live, and that the fourteenth amendment protects them on a federal level, not on a state level.