The most common and most likely answer to this crossword clue is the 3 plus 5 plus 4 letter word OLD WIVES TALE
I've seen this crossword clue in The Daily Telegraph
O
L
D
W
I
V
E
S
T
A
L
E
More clues leading to the result OLD WIVES TALE
- This saw Violet led astray?
- Head off common ailment with view shaped by outdated example of folk wisdom
- Incredible story Wilde’s valet fabricated after love
- Daring to let slip initial view about outdated superstition
- Dispatched Devil to Wales? A superstition
- A lot led astray holding anarchic views must be a myth
- Worn-out elves wait for treatment in fairy story
Buddy explains!
The straight part
We know that "a myth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a myth = old wives tale.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.