Arena, somewhere you go round in reverse (4)
I believe the answer is:
oval
'arena' is the definition.
(the Oval is a cricket arena)
'somewhere you go round in reverse' is the wordplay.
'somewhere you go' becomes 'lav' (lavatory).
'round' becomes 'o' (round can mean a round object).
'in reverse' shows that the letters should be reversed in order.
'lav'+'o'='lavo'
'lavo' written backwards gives 'OVAL'.
(Other definitions for oval that I've seen before include "London cricket-ground" , "London cricket ground" , "Egg shape - Kennington test match venue" , "Squashed circle" , "Test site" .)