The most common and most likely answer to this crossword clue is the 8 letter word SCHOOLED
I've seen this crossword clue in Financial Times
S
C
H
O
O
L
E
D
Buddy explains!

The straight part
We know that "being taught a lesson" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case being taught a lesson = schooled.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 SCHOOLED mean?
SCHOOLED verb- (of fish) To form into, or travel in a school.
- To educate, teach, or train (often, but not necessarily, in a school).
- To defeat emphatically, to teach an opponent a harsh lesson.
- To control, or compose, one's expression.