Desperate fellow's hiding in Greek port (6)
I believe the answer is:
gdansk
'port' is the definition.
(port in Poland)
'desperate fellow's hiding in greek' is the wordplay.
'desperate fellow's' becomes 'dan's' (Desperate Dan is a comic book character).
'hiding in' indicates putting letters inside.
'greek' becomes 'gk'.
'dans' put into 'gk' is 'GDANSK'.
(Other definitions for gdansk that I've seen before include "Polish town" , "Polish seaport" , "It was once called Danzig" , "Polish Baltic port" , "Polish coastal city" .)