The most common and most likely answer to this crossword clue is the 5 letter word CRAZY
I've seen this crossword clue in The Guardian
C
R
A
Z
Y
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.
What does CRAZY mean?
CRAZY noun- An insane or eccentric person; a crackpot.
- Eccentric behaviour; lunacy.
- Flawed or damaged; unsound, liable to break apart; ramshackle.
- Sickly, frail; diseased.
- Of unsound mind; insane, demented.
- Out of control.
- Very excited or enthusiastic.
- In love; experiencing romantic feelings.
- Very unexpected; wildly surprising.
- Very, extremely.