Slim Italian shows restraint (5)
I believe the answer is:
limit
'restraint' is the definition.
(thesaurus)
'slim italian shows' is the wordplay.
'shows' indicates the answer is hidden within the clue.
'LIMIT' is hidden within 'slim italian'.
(Other definitions for limit that I've seen before include "border" , "end" , "Confine within bounds" , "Restrict - boundary" , "Cap" .)