Playing field's to one side (5)
I believe the answer is:
recto
'one side' is the definition.
(I've seen this before)
'playing field's to' is the wordplay.
'playing field' becomes 'rec' (short for recreation ground).
'rec'+'to'='RECTO'
(Other definitions for recto that I've seen before include "No leaves left" , "front of leaf" , "Right-hand pages of book" , "Page three, for example" , "one side" .)