Extra Norse works returned by daughter (5)
I believe the answer is:
added
'extra' is the definition.
(something added is extra)
'norse works returned by daughter' is the wordplay.
'norse works' becomes 'edda' (term for two Icelandic literary works).
'returned' shows that the letters should be reversed in order.
'by' says to put letters next to each other.
'daughter' becomes 'd' (genealogical abbreviation).
'edda' in reverse letter order is 'adde'.
'adde'+'d'='ADDED'
(Other definitions for added that I've seen before include "Said" , "Totted" , "Extra" , "Contributed" , "Summed up" .)