Pictorial representation of Greek character keeping fit (7)
I believe the answer is:
tableau
'pictorial representation' is the definition.
'greek character keeping fit' is the wordplay.
'greek character' becomes 'tau' (letter from the Greek alphabet).
'keeping' means one lot of letters goes inside another.
'fit' becomes 'able' (similar in meaning).
'tau' placed around 'able' is 'TABLEAU'.
'of' acts as a link.
(Other definitions for tableau that I've seen before include "Dramatic setting" , "Motionless figures representing a story" , "Scene of still figures" , "still life?" , "Dramatic scene (where the action is frozen?)" .)