Port, as in a bar, maybe (5)
I believe the answer is:
basra
'port' is the definition.
(I know that Basra is a port)
'as in a bar maybe' is the wordplay.
'in' means one lot of letters goes inside another.
'maybe' is an anagram indicator.
'bar' is an anagram of 'bra'.
'as' put inside 'bra' is 'BASRA'.
(Other definitions for basra that I've seen before include "Middle Eastern city" , "Iraqi port city" , "Iraqi city; Arabs (anag.)" , "City in Iraq" , "Chief port of Iraq" .)