Cheaper ratatouille includes ingredients that need refinement (6)
I believe the answer is:
errata
'ingredients that need refinement' is the definition.
(list of printing errors )
'cheaper ratatouille includes' is the wordplay.
'includes' indicates the answer is hidden within the clue.
'ERRATA' is hidden within 'cheaper ratatouille'.
(Other definitions for errata that I've seen before include "List of misprints" , "Boobs in a book" , "List of printing mistakes" , "Mistakes in printed material" , "Listed errors" .)