Song using a new, recurring melody for the most part (6)
I believe the answer is:
anthem
'song' is the definition.
(anthem is a kind of song)
'a new recurring melody for the most part' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'recurring melody' becomes 'theme' (I've seen this in another clue).
'for the most part' means to remove the last letter (most but not all of the letters).
'theme' with its last letter taken off is 'them'.
'a'+'n'+'them'='ANTHEM'
'using' acts as a link.
(Other definitions for anthem that I've seen before include "Song in praise of a nation" , "Uplifting song -- the man (anag)" , "National hymn" , "Uplifting music" , "The man for a popular song" .)