Influential Italians lose one physician (5)
I believe the answer is:
medic
'physician' is the definition.
(I've seen this before)
'influential italians lose one' is the wordplay.
I cannot really understand how this works, but
'one' could be 'me' (a setter might use 'one' to humourously mean 'me') and 'me' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for medic that I've seen before include "Health worker" , "Word for 'doctor'" , "Eg, doctor" , "What was Basutoland" , "He may offer treatment" .)