Show maltreatment involving Italian restaurant (10)
I believe the answer is:
Here is my best explanation:
'show' is the definition.
(illustrating is a kind of showing)
'maltreatment involving italian restaurant' is the subsidiary indication.
'maltreatment' becomes 'illuse' (I've seen this before).
'involving' indicates putting letters inside.
'italian restaurant' becomes 'trat' (I've seen this in other clues).
'illuse' going around 'trat' is 'illustrate'.
(Other definitions for illustrate that I've seen before include "Exemplify", "Explain with pictures", "Provide with pictures", "picture", "Ornament", "Give as example", "Show" and "show".)