Migrating bird is in an Italian port (8)
I believe the answer is:
brindisi
'an italian port' is the definition.
(I've seen this before)
'migrating bird is in' is the wordplay.
'migrating' indicates anagramming the letters (I've seen 'migrate' mean this).
'bird'+'is'+'in'='birdisin'
'birdisin' is an anagram of 'BRINDISI'.
(Other definitions for brindisi that I've seen before include "Southeast Italian port" , "toast of some Italians" , "Italian port on the Adriatic" , "Italian drinking song" , "Song that goes with drinking" .)