Observe the timekeeper (5)
I believe the answer is:
watch
I believe this is a double definition.
'observe' is the first definition.
(synonyms)
'the timekeeper' is the second definition.
(watch is a kind of timekeeper)
(Other definitions for watch that I've seen before include "period of duty" , "Observe - guard" , "Observe - timepiece" , "View" , "Keep an eye on - timepiece" .)