Threat by the Italian (5)
I believe the answer is:
peril
'threat' is the definition.
(thesaurus)
'by the italian' is the wordplay.
'by' becomes 'per'.
'the italian' becomes 'il' (the in Italian).
'per'+'il'='PERIL'
(Other definitions for peril that I've seen before include "risk" , "Quest" , "Immediate danger" , "Danger, hazard" , "Source of danger" .)