Sentence:  "What! Roscoe?" inquired the principal. / "Yes." / "Is he in any mischief?" / "Mischief? I should say so! Why, he's a regular <WSD>young Turk</WSD>." / "A <WSD>young Turk</WSD>? I don't think I understand you, James." / "I mean, he's a young ruffian." 
Meaning of the word marked with <WSD> tags:  A young person who agitates for political or other reform; a young person with a rebellious disposition.