timekeeper

US /ˈtaɪmˌkiː.pɚ/
UK /ˈtaɪmˌkiː.pɚ/
1.

máy chấm công

an object or person that records (an amount of) time:

:
There's no point in having a clock which looks attractive if it isn't a good timekeeper (= if it doesn't show the correct time).