Go across island, reaching Italian city (5)
I believe the answer is:
turin
'italian city' is the definition.
(I know that Turin is Italian)
'go across island' is the wordplay.
'go' becomes 'turn' (as in one's go or turn in a game).
'across' indicates putting letters inside.
'island' becomes 'i' (geographical abbreviation).
'turn' enclosing 'i' is 'TURIN'.
'reaching' is the link.
(Other definitions for turin that I've seen before include "I turn to the Italian city" , "Italian destination" , "First capital in 1861 of united Italy" , "Italian city with sacred Christian Shroud" , "Italian location" .)