Yes, Mr. Blue by Myles Connolly is a clean book.

The novel follows the life of J. Blue, a man who inherits a vast fortune only to discard his wealth in favor of a life of intentional poverty and service. Inspired by the spirit of St. Francis of Assisi, the protagonist lives in a large packing box on a skyscraper rooftop in New York City, viewing the world through a lens of profound wonder and religious idealism.