Car's rev counter (10)

I believe the answer is:

tachometer

(Other definitions for tachometer that I've seen before include "Instrument measuring speed of rotation" , "It measures revolutions" , "rev counter" , "Teacher Tom (anag.)" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.