Go to bed in Italian city around noon (4,2)
I believe the answer is:
turn in
'go to bed' is the definition.
(synonyms)
'italian city around noon' is the wordplay.
'italian city' becomes 'turin' (I've seen this in another clue).
'around' indicates putting letters inside.
'noon' becomes 'n' (abbreviation for noon).
'turin' placed around 'n' is 'TURN-IN'.
'in' acts as a link.
(Other definitions for turn in that I've seen before include "Hand over - retire" , "Prepare for sleep" , "Retire to bed" , "Hit the hay" , "Go to bed, changing direction" .)