The most common and most likely answer to this crossword clue is the 9 letter word HERCULEAN
I've seen this crossword clue in The Guardian
H
E
R
C
U
L
E
A
N
More clues leading to the result HERCULEAN
- Massive re-launch organised around the end of June
- Female copper, slim and incredibly powerful
- That man with nuclear particles is extremely difficult
- Strong as Poirot?
- An ulcer he developed from labour, hard and dangerous
- List suppressed by that female copper is very dangerous
- Woman’s article about cryptic clue of remarkable strength
- Massive star, practically perfect, embracing ‘Posh’
- Powerful explosive with nuclear bomb
- The female copper — thin or big and strong?
Buddy explains!
The straight part
We know that "very hard" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case very hard = herculean.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 HERCULEAN mean?
HERCULEAN adjective- Of extraordinary might, power, size, etc.; suggesting Hercules in size or strength.
- Requiring a huge amount of work; of extraordinary difficulty.