Rubbish round Madrid arena (8)
I believe the answer is:
bullring
'madrid arena' is the definition.
(bullfighting is popular in Madrid)
'rubbish round' is the wordplay.
'rubbish' becomes 'bull' (I've seen this before).
'round' becomes 'ring' (synonyms).
'bull'+'ring'='BULLRING'
(Other definitions for bullring that I've seen before include "public arena" , "Location in Carmen" , "Enclosure for cruel sport (in Birmingham?)" , "Arena in Spain" .)