Regard as a spectator (4,2)
I believe the answer is:
look on
'regard' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for look on that I've seen before include "Be a spectator, watch" , "Watch as observer - dont get involved" , "Watch without becoming involved" , "Stand by watching, observe" , "Be a spectator, observe" .)