Pen new melody for deity (7)
I believe the answer is:
neptune
'for deity' is the definition.
(Neptune is an example)
'pen new melody' is the wordplay.
'new' indicates anagramming the letters.
'melody' becomes 'tune' (synonyms).
'pen' anagrammed gives 'nep'.
'nep'+'tune'='NEPTUNE'
(Other definitions for neptune that I've seen before include "King of the sea" , "heavenly body" , "one of the Planets" , "Planet, identified 1846" , "Eighth rock from the Sun" .)