The most common and most likely answer to this crossword clue is the 7 letter word CRETINS
I've seen this crossword clue in Financial Times
C
R
E
T
I
N
S
Buddy explains!
The straight part
We know that "idiots" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case idiots = cretins.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 CRETINS mean?
CRETINS noun- A person who fails to develop mentally and physically due to a congenital hypothyroidism.
- (by extension) An idiot.