An individual soft on Norse criminal (6)
I believe the answer is:
person
'an individual' is the definition.
('person' can be a synonym of 'individual')
'soft on norse criminal' is the wordplay.
'soft' becomes 'p' (musical abbreviation for 'piano'**).
'on' indicates putting letters inside.
'criminal' is an anagram indicator.
'norse' anagrammed gives 'erson'.
'p' placed inside 'erson' is 'PERSON'.
(Other definitions for person that I've seen before include "Type" , "Bod" , "anyone else" , "See 17" , "A man or woman" .)