Picture one game being played (5)
I believe the answer is:
image
'picture' is the definition.
(synonyms)
'one game being played' is the wordplay.
'one' becomes 'i' (Roman numeral).
'being played' is an anagram indicator (letters playing around).
'game' anagrammed 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" .)