Surrounds the arenas (5)
I believe the answer is:
rings
This could be a double definition.
'surrounds' is the first definition.
('ring' can be a synonym of 'surround')
'the arenas' is the second definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Maybe there's a link between them I don't understand?
Can you help me to learn more?
(Other definitions for rings that I've seen before include "Makes a circuit" , "Spaces used for boxing" , "Calls; circles" , "Small circles or bands for the finger" , "Encircles" .)