The most common and most likely answer to this crossword clue is the 5 letter word GONZO
I've seen this crossword clue in The Times
G
O
N
Z
O
Buddy explains!
The straight part
We know that "Crazy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case crazy = gonzo.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 GONZO mean?
GONZO noun- Gonzo journalism or a journalist who produces such journalism.
- A wild or crazy person.
- Using an unconventional, exaggerated and highly subjective style, often when the reporter takes part in the events of the story.
- Unconventional, bizarre, crazy.