Song to develop: originally called press for review (4,2,6)
I believe the answer is:
come on eileen
'song' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'develop originally called press for review' is the wordplay.
'develop' becomes 'come on' (coming on is a kind of developing).
'originally' becomes 'nee' (I've seen this in another clue).
'called press' becomes 'lie' (I can't explain this - if you can you should believe this answer much more).
'for review' says the letters should be written backwards.
'nee'+'lie'='neelie'
'neelie' reversed gives 'eileen'.
'comeon'+'eileen'='COME ON EILEEN'
'to' acts as a link.
Can you help me to learn more?