Story of the picture? (4)
I believe the answer is:
epic
'story' is the definition.
(I have seen 'Heroic story' mean 'epic' so perhaps 'story' could also mean 'epic')
'of the picture?' is the wordplay.
'of' indicates the answer is hidden within the clue.
'EPIC' is hidden in the letters of 'the picture'.
(Other definitions for epic that I've seen before include "Long story telling of a hero's deeds" , "imposing" , "of impressive proportions?" , "eg The Iliad" , "Heroic poem, film" .)