Pen new melody for a god (7)
I believe the answer is:
neptune
'for a god' is the definition.
(Neptune is an example)
'pen new melody' is the wordplay.
'new' indicates anagramming the letters.
'melody' becomes 'tune' (synonyms).
'pen' is an anagram of 'nep'.
'nep'+'tune'='NEPTUNE'
(Other definitions for neptune that I've seen before include "Holst composed it" , "Holst piece" , "Roman sea god - planet" , "Poseidon" , "musical work" .)