Notice a speedometer (5)
I believe the answer is:
clock
This clue might be a double definition.
'notice' is the first definition.
(I've seen this before)
'a speedometer' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?
Can you help me to learn more?
(Other definitions for clock that I've seen before include "a person's face" , "Striker" , "Time-teller" , "Watch" , "time" .)