Crossword Genius

Song so titled after rewriting (4,2,2)

Ross

I believe the answer is:

lets do it

'song' is the definition.
(Cole Porter song)

'so titled after rewriting' is the wordplay.
'after' says to put letters next to each other.
'rewriting' indicates anagramming the letters.
'so'+'titled'='sotitled'
'sotitled' anagrammed gives 'LETS DO IT'.

I've seen this clue in The Times.
Want a hint initially instead of a full solution? Install my app