Special delivery at a conference

KEYNOTE

This opening speech often sets the tone for the entire event and is typically given by a prominent figure. Think of the word that combines "key" with a musical or spoken presentation.

Special delivery" hints at something important being presented, while "at a conference" points to a formal event. The answer plays on "keynote," which is both the main speech at a gathering and a musical term (the note that defines a key). Here, it’s the highlight talk, making it a clever fit for a 'special' presentation.