The birthplace of Christopher Columbus (5)
I believe the answer is:
genoa
'the birthplace of christopher columbus' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for genoa that I've seen before include "Seaport in northwestern Italy" , "Cake type; foresail" , "Italian city has no age, oddly" , "Italian city; sail" , "City of Italy" .)