See vessel lays up back in Black Sea port (10)
I believe the answer is:
sevastopol
'black sea port' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe there's a link between them I don't understand?
'see vessel lays up back' is the wordplay.
'see' becomes 'lo' (archaic exclamation meaning 'look!').
'vessel' becomes 'pot' (type of container).
'lays up' becomes 'saves' (I am not sure about this - if you are sure you should believe this answer much more).
'back' says the letters should be written backwards.
'lo'+'pot'+'saves'='lopotsaves'
'lopotsaves' back-to-front is 'SEVASTOPOL'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for sevastopol that I've seen before include "site of naval base" , "port in Ukraine" , "Black Sea resort" .)