In the examples taught here, a defective verb has a marfu ism and a mansub khabar.
Use two questions:
- Who or what is being described? That noun is the marfu ism.
- What state or description is given? That is the mansub khabar.
In صَارَ الْفَقِيرُ غَنِيًّا, the sentence is about الْفَقِيرُ, while غَنِيًّا tells his new state.
Do not make both nouns mansub.