Idea unacceptable about Italy (6)
I believe the answer is:
notion
'idea' is the definition.
(notion is a kind of idea)
'unacceptable about italy' is the wordplay.
'unacceptable' becomes 'not on' (something 'not on' is unacceptable or frowned upon).
'about' indicates putting letters inside.
'italy' becomes 'i'.
'noton' placed around 'i' is 'NOTION'.
(Other definitions for notion that I've seen before include "Whimsical idea or small sewing article" , "Idea, concept" , "Idea or fancy" , "Vague impression" , "Concept, belief" .)