Concerned with northern Scandinavian’s pronounced regression (7)
I believe the answer is:
relapse
'pronounced regression' is the definition.
'relapse' can be an answer for 'regression' (thesaurus). I'm not certain of the 'pronounced' bit.
'concerned with northern scandinavian's' is the wordplay.
'concerned with' becomes 're' (re can mean regarding or about).
'northern scandinavian's' becomes 'lapse' (I am not sure about this - if you are sure you should believe this answer much more).
're'+'lapse'='RELAPSE'
Can you help me to learn more?
(Other definitions for relapse that I've seen before include "Slip back to former state" , "Pleaser may slip to earlier state" , "Become sick again" , "Failure to maintain a higher state" , "Deterioration after period of improvement" .)