Portrait may show one's years after time inside (5)
I believe the answer is:
image
'portrait' is the definition.
(I've seen this in another clue)
'one's years after time inside' is the wordplay.
'one's years' becomes 'age'.
'after' says to put letters next to each other.
'inside' says to take the centre.
The middle of 'time' is 'im'.
'age' after 'im' is 'IMAGE'.
'may show' acts as a link.
(Other definitions for image that I've seen before include "Vision" , "Reflection" , "Public persona" , "Representation, picture" , "Epitome" .)