Please guide me for the part of speech of clean here in this extract:
He had schooled him in the evils that befall prophets; in those that come from the world, which are trifling, and those that come from the Lord and burn the prophet clean;
for he himse lfhimself had been burned clean and burned clean again. He had learned by fire.
Excerpt from The Violent Bear It Away, by Flannery O’Connor.