Onlooker, spectator (8)
I believe the answer is:
observer
I believe this is a double definition.
'onlooker' is the first definition.
(I've seen this in another clue)
'spectator' is the second definition.
(I've seen this before)
(Other definitions for observer that I've seen before include "broadsheet" , "One who watches" , "Looker-on" , "One watching, evaluating" , "Non-participant; a paper" .)