The most common and most likely answer to this crossword clue is the 9 letter word SOLILOQUY
I've seen this crossword clue in The Guardian
S
O
L
I
L
O
Q
U
Y
More clues leading to the result SOLILOQUY
Buddy explains!

The straight part
We know that "speech" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case speech = soliloquy.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SOLILOQUY mean?
SOLILOQUY noun- The act of a character speaking to themselves so as to reveal their thoughts to the audience.
- (authorship) A speech or written discourse in this form.
- (very rare) To issue a soliloquy.