Area near ground, or the ground itself (5)
I believe the answer is:
arena
'the ground itself' is the definition.
(sports ground)
'area near ground' is the wordplay.
'area' becomes 'a' (maths abbreviation).
'ground' indicates anagramming the letters ('grind' the letters into a new form).
'near' with letters rearranged gives 'rena'.
'a'+'rena'='ARENA'
'or' acts as a link.
(Other definitions for arena that I've seen before include "Gladiatorial venue" , "place involving conflict?" , "Place of activity, especially conflict" , "Amphitheatre's central space" , "Ring; stage" .)