American near Barking Stadium (5)
I believe the answer is:
arena
'stadium' is the definition.
(eg a sports arena)
'american near barking' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'barking' indicates anagramming the letters (UK slang for mad).
'near' with letters rearranged gives 'rena'.
'a'+'rena'='ARENA'
(Other definitions for arena that I've seen before include "Sit around here being entertained" , "sports ground" , "Gladiatorial ring" , "Engagement ring" , "Sporting venue enclosed by seats" .)