The most common and most likely answer to this crossword clue is the 9 letter word DISABUSED
I've seen this crossword clue in The Daily Telegraph
D
I
S
A
B
U
S
E
D
More clues leading to the result DISABUSED
Buddy explains!
The straight part
We know that "set free from wrong ideas" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case set free from wrong ideas = disabused.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 DISABUSED mean?
DISABUSED verb- To free (someone) of a misconception or misapprehension; to unveil a falsehood held by (somebody).