Английский словарь американских идиом - keep one's nose clean

{v. phr.}, {slang} To stay out of trouble; do only what you should do. * /The boss said Jim could have the job as long as he kept his nose clean and worked hard./ * /The policeman warned the boys to keep their noses clean unless they wanted to go to jail./ Compare: STEER CLEAR OF(2).