Influence unsettling camp hosted by Italian (6)
I believe the answer is:
impact
'influence' is the definition.
(impact is a kind of influence)
'unsettling camp hosted by italian' is the wordplay.
'unsettling' is an anagram indicator.
'hosted by' means one lot of letters goes inside another.
'italian' becomes 'it'.
'camp' is an anagram of 'mpac'.
'mpac' going within 'it' is 'IMPACT'.
(Other definitions for impact that I've seen before include "The striking of one body against another" , "Force or shock of a collision" , "Marked effect or influence" , "Force of blow or collision" , "Force exerted by collision" .)