Rum does when served up -- and port (6)
I believe the answer is:
odessa
'port' is the definition.
(I've seen this before)
'rum does when served up' is the wordplay.
'rum' indicates an anagram (rum can mean strange or unusual).
'when' becomes 'as'.
'served up' is a reversal indicator.
'as' in reverse letter order is 'sa'.
'does' anagrammed gives 'odes'.
'odes'+'sa'='ODESSA'
'and' acts as a link.
(Other definitions for odessa that I've seen before include "Do seas come into Ukrainian city?" , "Ukrainian location" , "Black Sea location" , "Ukrainian naval base" , "Ukrainian Black Sea port" .)