Lacking in confidence, not very bright Italian turned up (5)
I believe the answer is:
timid
'lacking in confidence' is the definition.
(I've seen this before)
'not very bright italian turned up' is the wordplay.
'not very bright' becomes 'dim' (I've seen this before).
'italian' becomes 'it'.
'turned up' says the letters should be written in reverse.
'dim'+'it'='dimit'
'dimit' back-to-front is 'TIMID'.
(Other definitions for timid that I've seen before include "Diffident, faint-hearted" , "Easily scared" , "afraid to speak out?" , "Fearful - shy" , "Pusillanimous" .)