The most common and most likely answer to this crossword clue is the 2 plus 3 letter word MY HAT
I've seen this crossword clue in Financial Times
M
Y
H
A
T
More clues leading to the result MY HAT
- Nonsense that’s over the setter’s head!
- Some chant a hymn backwards? It’s nonsense
- … compiler wears this bowler out? Oh, please!
- Banks of money going to Panama? I don’t believe it!
- Maiden’s heart regularly broken by Yankee? I don’t believe it!
- Might this be going to this setter’s head? Nonsense!
- A myth, terrible nonsense
- A myth? Awful nonsense
- Rubbish a myth as false
- I might tip this rubbish!
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.