The most common and most likely answer to this crossword clue is the 6 letter word DUMBOS
I've seen this crossword clue in The Guardian
D
U
M
B
O
S
Buddy explains!
The straight part
We know that "Fools" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fools = dumbos.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 DUMBOS mean?
DUMBOS noun- A stupid person.
- "Stupid person," by 1951, American English, from dumb. The Disney musical cartoon is from 1941; in it the elephant's name is a mocking nickname based on Jumbo.