Friend across the pond served up excellent port (5)
I believe the answer is:
dubai
'port' is the definition.
(UAE port city)
'friend across the pond served up excellent' is the wordplay.
I cannot quite see how this works, but
'excellent' could be 'ai' (resembles 'A1', old-fashioned term for excellent) and 'ai' is found in the answer.
The remaining letters 'dub' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dubai that I've seen before include "One of the UAE and its capital" , "capital and port" , "Gulf sheikhdom" , "Gulf emirate and port city" , "Port city on the Persian Gulf" .)