The most common and most likely answer to this crossword clue is the 9 letter word NUMBSKULL
N
U
M
B
S
K
U
L
L
More clues leading to the result NUMBSKULL
- Charlie no longer operating, welcomes doctors into country
- Result of dental anaesthesia overdose? Idiot!
- Deadhead? Quite literally!
- Fool gets cold on rowing boat reportedly
- Said to row after dull fool
- Dummy’s useless without my blank spades king unblocking, for starters
- Senseless row on the phone with Charlie
Buddy explains!

The straight part
We know that "fool" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fool = numbskull.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 NUMBSKULL mean?
NUMBSKULL noun- A dunce, mentally dull or stupid person.
- A person who refuses to learn or grow mentally.
- A traditional name for a fool who serves as the butt of jokes about stupidity.