A nincompoop necking nip of nice port (7)
I believe the answer is:
antwerp
'port' is the definition.
(Belgian port)
'a nincompoop' is the wordplay.
'a' becomes 'an'.
'nincompoop' becomes 'twerp' (I've seen this before).
'an'+'twerp'='ANTWERP'
'necking nip of nice' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for antwerp that I've seen before include "North Belgian port" , "Belgian city port" , "War-damaged city" , "Wrap net around this Belgian city" , "North Sea port" .)