Japanese copper married in part of Scandinavia (6)
I believe the answer is:
sweden
'part of scandinavia' is the definition.
(Sweden is in Scandinavia)
'japanese copper married in' is the wordplay.
'japanese copper' becomes 'sen' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'married' becomes 'wed' (wed can mean married).
'in' indicates putting letters inside.
'sen' going around 'wed' is 'SWEDEN'.
Can you help me to learn more?
(Other definitions for sweden that I've seen before include "land" , "Stockholm's country" , "We send to Scandinavian country" , "Baltic country" , "We send out to the northern state" .)