The most common and most likely answer to this crossword clue is the 5 plus 4 letter word MARCH HARE
I've seen this crossword clue in Financial Times
M
A
R
C
H
H
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More clues leading to the result MARCH HARE
- One in Tea Party to advance career
- A month on speed? People say I’m mad
- Animal that finds itself nuts in spring?
- I attended the Hatter’s tea party to protest before race
- Charm her with a mad tea party guest!
- Run after tramp, proverbial whacko
- Party guest and husband are on parade
- I joined 14’s party to protest before race
- Alice’s companion gets to walk, then run
- Walk and run with Alice's companion
Buddy explains!
The straight part
We know that "People say I’m mad" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case people say i’m mad = march hare.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.