Opening words (5)
I believe the answer is:
intro
'opening words' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for intro that I've seen before include "First part of a news story (abbr)" , "Lead-in" , "Brief passage to start a piece of popular music" , "Opening passage (abbr)" , "Prologue, opening (abbr.)" .)