Sentence:  The doctor now obeys the summons, / Likes both his company and commons; / Displays his talent, sits till ten; Next day invited, comes again; / Soon grows domestic, seldom fails, / Either at morning or at meals; / Came early, and departed late; / In short, the <WSD>gudgeon</WSD> took the bait. 
Meaning of the word marked with <WSD> tags:  An idiot; a person easily duped or cheated.