English port in separate country (10)
I believe the answer is:
sunderland
'english port' is the definition.
The definition suggests a singular noun which matches the answer.
'separate country' is the wordplay.
'separate' becomes 'sunder' (I've seen this in another clue).
'country' becomes 'land' (synonyms).
'sunder'+'land'='SUNDERLAND'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for sunderland that I've seen before include "Winners of forty years back" , "City near 17[STOCKTON]" , "Port near Newcastle" , "City on the River Wear" , "City of NE England" .)