Scoundrel and lunatic brought up in N Sea port (9)
I believe the answer is:
rotterdam
'port' is the definition.
(I know that Rotterdam is a port)
'scoundrel and lunatic brought up' is the wordplay.
'scoundrel' becomes 'rotter' (both can mean a nasty person).
'and' means one lot of letters go next to another.
'lunatic' becomes 'mad' (I've seen this before).
'brought up' shows that the letters should be reversed in order (in a down clue, letters go up).
'mad' back-to-front is 'dam'.
'rotter'+'dam'='ROTTERDAM'
'in n sea' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for rotterdam that I've seen before include "Dutch city and port" , "Major world seaport at the mouth of the Meuse" , "European port" , "One of the world's largest ports" , "Netherlands port" .)