How you may need to start a song? (4)
I believe the answer is:
hymn
'a song?' is the definition.
(thesaurus)
'how you may need to start' is the wordplay.
'to start' says to take the initial letters.
The first letters of 'how you may need' is 'HYMN'.
(Other definitions for hymn that I've seen before include "religious works" , "Orison" , "Song in praise of 22 down" , "Godly song" , "Special song" .)