Kick-off of game upset spectators (4)
I believe the answer is:
gate
'spectators' is the definition.
(I've seen this before)
'kick-off of game upset' is the wordplay.
'kick-off of game' becomes 'g' (I can't explain this - if you can you should believe this answer much more).
'upset' becomes 'ate' (to eat up is worry or upset).
'g'+'ate'='GATE'
Can you help me to learn more?
(Other definitions for gate that I've seen before include "Attendance; entrance" , "Facility in airport" , "Garden door?" , "Five-bar opening?" , "Kind of door as in wall or fence" .)