Act as observer (3)
I believe the answer is:
see
This could be a double definition.
'act' is the first definition.
(I know that see is a type of affiliate)
'observer' is the second definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for see that I've seen before include "Set eyes on" , "Perceive; diocese" , "Bishop's diocese" , "Realize" , "Receive" .)