“What can cause the uncaused?”
I’m inferring that that there are two levels of causation, both unseen: That which is referred to as “uncaused” and that which “causes”.
I will flip it around into sentences with subjects:
Let us assume that x is the cause of the y.
The y is referred to as “the uncaused”.
The reason y is referred to as “the uncaused” is because we have not yet determined the cause of y or we have no desire to determine the cause of y or we have concluded that y has no cause.
Our goal is to determine if y has a cause. If y has a cause, we will refer to x as the cause of the y. At present, we are only assuming the x is the cause of the y and have not determined such.