Scandinavian mostly adopting married standards (5)
I believe the answer is:
norms
'standards' is the definition.
(norm is a kind of standard)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for norms that I've seen before include "Standards of customary behaviour" , "Social standards" , "Standards, customs of behaviour" , "They're usual or standard" , "Representative standards as of behaviour" .)