Scan the melody in part song (6)
I believe the answer is:
anthem
'song' is the definition.
(anthem is a kind of song)
'scan the melody in part' is the wordplay.
'in part' says the answer is hidden in the clue.
'ANTHEM' is hidden within 'scan the melody'.
(Other definitions for anthem that I've seen before include "Song in praise of a nation" , "Church choral piece" , "National or religious song" , "Religious chant" , "Hymn of loyalty" .)