Observe co-worker (4)
I believe the answer is:
peer
This might be a double definition.
'observe' is the first definition.
(thesaurus)
'co-worker' is the second definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see a link between them that I don't see?
Can you help me to learn more?
(Other definitions for peer that I've seen before include "One's equal" , "Person of equal standing" , "Struggle to see; equal" , "Look dimly at lord" , "one visiting ladies, say?" .)