Perhaps writer of Happy Birthday's more friendly not initially (4)
I believe the answer is:
info
'perhaps writer' is the definition.
(I know that writer is a profession)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for info that I've seen before include "Facts; knowledge gained" , "News" , "Latest" , "Gen (colloq.)" , "Dope" .)