Section governed by young man seizing Northern port (10)
I believe the answer is:
sunderland
'port' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I don't see?
'section governed by young man seizing northern' is the wordplay.
'section' becomes 's' (legal abbreviation).
'governed by' becomes 'under' (I've seen this before).
'young man' becomes 'lad' (lad can mean a boy or young man).
'seizing' indicates putting letters inside (inserted letters are seized).
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'lad' placed around 'n' is 'land'.
's'+'under'+'land'='SUNDERLAND'
Can you help me to learn more?
(Other definitions for sunderland that I've seen before include "City on the River Wear" , "Footballers" , "Port near Newcastle" , "City near 17[STOCKTON]" , "Winners of forty years back" .)