Build new Northern capital (6)
I believe the answer is:
dublin
'capital' is the definition.
(Dublin is an example)
'build new northern' is the wordplay.
'new' is an anagram indicator.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'build' is an anagram of 'dubli'.
'dubli'+'n'='DUBLIN'
(Other definitions for dublin that I've seen before include "European city" , "City of 1 across" , "European capital" , "Ulysses city (Joyce)" , "Capital of 8" .)