Stadiums (6)
I believe the answer is:
arenas
'stadiums' is the definition.
('arena' can be a synonym of 'stadium')
This is all the clue.
(Other definitions for arenas that I've seen before include "Structures for open-air events" , "A snare for central parts of amphitheatres" , "Areas of endeavours" , "Stadia" , "Spaces for sports events" .)