Show maltreatment involving Italian restaurant (10)
I believe the answer is:
illustrate
'show' is the definition.
(I've seen this before)
'maltreatment involving italian restaurant' is the wordplay.
'maltreatment' becomes 'illuse' (I've seen this before).
'involving' means one lot of letters goes inside another.
'italian restaurant' becomes 'trat' (I've seen this in other clues).
'illuse' enclosing 'trat' is 'ILLUSTRATE'.
(Other definitions for illustrate that I've seen before include "Explain with pictures" , "Provide with pictures" , "picture" , "Ornament" , "Give as example" .)