Misconception about flan served up for example (12)
I believe the answer is:
illustration
'example' is the definition.
(I know that example can be written as illustration)
'misconception about flan served up' is the wordplay.
'misconception' becomes 'illusion' (illusion is a kind of misconception).
'about' indicates putting letters inside.
'flan' becomes 'tart' (I've seen this before).
'served up' says the letters should be written in reverse (in a down clue, going upwards).
'tart' backwards is 'trat'.
'illusion' enclosing 'trat' is 'ILLUSTRATION'.
'for' is the link.
(Other definitions for illustration that I've seen before include "Picture in a book or periodical" , "Sample" , "Picture; example" , "Drawing - example" , "plate" .)