I confess that I didn't pick up The Clown for any literary reason at all. I was interested in this book entirely because the book promised to be about a mime. It was only after that I learned anything about Heinrich Böll. The essentials on Böll are that he is a German novelist, Nobel Prize 1972, grew up in a respectable Catholic pacifist family in World War II. From this book, it seems that he has inherited his parents' distaste for war, though they also seem to have turned him against certain aspects of Catholicism and respectability.
The Clown, in spite of its title, is a rather dreary book, punctuated only rarely by moments of comedy, which sometimes come simply from the dreariness reaching such heights as to be comical.