Exclude one Italian port (4)
I believe the answer is:
bari
'italian port' is the definition.
(I've seen this in another clue)
'exclude one' is the wordplay.
'exclude' becomes 'bar' (synonyms).
'one' becomes 'i' (Roman numeral).
'bar'+'i'='BARI'
(Other definitions for bari that I've seen before include "Adriatic resort" , "Adriatic seaport" , "Adriatic port" .)