Dog equipment in outskirts of arena (5)
I believe the answer is:
akita
'dog' is the definition.
(Akita is a breed of dog)
'equipment in outskirts of arena' is the wordplay.
'equipment' becomes 'kit' (kit is a kind of equipment).
'in' means one lot of letters goes inside another.
'outskirts of' means to remove the middle letters (only letters on the outskirts).
'arena' with its centre removed is 'aa'.
'kit' put inside 'aa' is 'AKITA'.
(Other definitions for akita that I've seen before include "Japanese breed of dog" , "heavy brute?" , "powerful dog" , "dog from Japan" .)