Rotter involved in riot at vandalised eatery (9)
I believe the answer is:
trattoria
'eatery' is the definition.
(I know that trattoria is a type of eatery)
'rotter involved in riot at' is the wordplay.
'rotter' becomes 'tra' (I am not sure about this - if you are sure you should believe this answer much more).
'involved in' indicates an anagram (involved can mean complex or confusing).
'riot'+'at'='riotat'
'riotat' is an anagram of 'ttoria'.
'tra'+'ttoria'='TRATTORIA'
'vandalised' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for trattoria that I've seen before include "Italian restaurant" , "Place to eat" , "where Italians eat" , "Italian eating establishment" .)