North Sea port offering little work during peak (6)
I believe the answer is:
bergen
'north sea port' is the definition.
(Norwegian city)
'little work during peak' is the wordplay.
'little work' becomes 'erg' (erg is a scientific unit for work).
'during' indicates putting letters inside.
'peak' becomes 'ben' (I've seen this before).
'erg' going within 'ben' is 'BERGEN'.
'offering' acts as a link.
(Other definitions for bergen that I've seen before include "SW Norway port" , "Norwegian port city" , "Port city of Norway" , "Second city of Norway" .)