The most common and most likely answer to this crossword clue is the 9 letter word CAUTIONED
I've seen this crossword clue in The Guardian
C
A
U
T
I
O
N
E
D
Buddy explains!

The straight part
We know that "Admonished" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case admonished = cautioned.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 CAUTIONED mean?
CAUTIONED verb- To warn; to alert, advise that caution is warranted.
- To give a yellow card