She wants us to eat a good breakfast.
NOT A TEACHER
Hello,
If I understand my sources correctly, there are at least two ways to analyze your sentence.
1. "us to eat a good breakfast" is an infinitive phrase/clause that is the object of the verb "wants."
a. "us" is the subject of the infinitive phrase/clause.
b. Your sentence is the accepted way to say "She wants that we eat a good breakfast," which -- as one of my sources would say-- sounds "strange" or "unidiomatic."
2. You can also say that "us" is the direct object of "wants."
a. Then, the infinitive phrase/clause "to eat a good breakfast" is an objective complement. That is to say, "to eat a good breakfast" complements (completes) the meaning of the object "us."
*****
Be very careful though. Look at "We promised her to come."
Who promised to come? "We" did, not "her." Therefore, "her" is the indirect object, and "to come" is the direct object of "promised."
Sources: Paul Roberts,
Understanding English (1954), pages 360 and 362; Pence and Emery,
A Grammar of Present-Day English (1947 and 1963), page 72.