The term CLUE FOR A CAR MECHANIC can be broken down into two crossword solutions: NOISE (5 letters) and RATTLE (6 letters). NOISE is a sound that is usually unwanted and can be caused by a variety of sources. It can be caused by mechanical issues, such as a loose part or a worn out bearing. RATTLE is a type of NOISE that is usually caused by something loose inside the car, such as a loose part or a worn out bearing. Both of these clues can be used to help a car mechanic diagnose a problem with a car.