Picture one game being played (5)
I believe the answer is:
image
'picture' is the definition.
(I know that picture can be written as image)
'one game being played' is the wordplay.
'one' becomes 'i' (Roman numeral).
'being played' indicates anagramming the letters (letters playing around).
'game' with letters rearranged gives 'mage'.
'i'+'mage'='IMAGE'
(Other definitions for image that I've seen before include "Pictorial representation" , "Public impression" , "Portrait, picture" , "Representation, picture" , "Visible impression" .)