Level playing field (5)
I believe the answer is:
pitch
This clue is a double definition.
'level' is the first definition.
(I have seen 'Level of sound' mean 'pitch' so perhaps 'level' could also mean 'pitch')
'playing field' is the second definition.
(I've seen this before)
(Other definitions for pitch that I've seen before include "Football ground" , "Throw - black stuff" , "perfect for some players" , "Set up a tent" , "Throw - bitumen" .)