The most common and most likely answer to this crossword clue is the 9 letter word SERMONISE
I've seen this crossword clue in The Daily Telegraph
S
E
R
M
O
N
I
S
E
More clues leading to the result SERMONISE
Buddy explains!

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 SERMONISE mean?
SERMONISE verb- To speak in the manner of a sermon; to preach; to propagate one's morality or opinions with speech.
- To preach a sermon to (somebody); to give (somebody) instruction or admonishment on the basis of one's morality or opinions.
- To say in the manner of a sermon or lecture.
- To inculcate rigid rules.