Sentence:  ... three things ought always to be kept under: a mastiff dog, a stone horse and a <WSD>clown</WSD>; and really I think a snarling, cross-grained <WSD>clown</WSD> to be the most unlucky beast of three. 
Meaning of the word marked with <WSD> tags:  A man of coarse nature and manners; an awkward fellow; an illbred person; a boor.