I am on time for the picture (5)
I believe the answer is:
image
'the picture' is the definition.
('image' can be a synonym of 'picture')
'i am on time for' is the wordplay.
'i am' becomes 'im'.
'on' is a charade indicator (letters next to each other).
'time for' becomes 'age' (I've seen this in other clues).
'im'+'age'='IMAGE'
(Other definitions for image that I've seen before include "Likeness of person or thing" , "Representation of person or thing" , "Portrait, picture" , "personality" , "Likeness; statue" .)