The most common and most likely answer to this crossword clue is the 9 letter word EXTREMELY
I've seen this crossword clue in Financial Times
E
X
T
R
E
M
E
L
Y
More clues leading to the result EXTREMELY
- Really how it appears for idealist?
- Very next note dropped by me in bank
- Utterly flummox Yankee with ‘1000 + 50 + 8’
- Axes elm tree that’s crooked to a large extent
- Extension to bank carries compiler remarkably
- Very cross with broken meter in city
- Pretty model T-rex seen by me in Cambridgeshire city
- Seriously stumbling experimentally; not terribly plain
- Very, very French — almost all attending Mass in old cathedral city
Buddy explains!

The straight part
We know that "Very" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case very = extremely.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 EXTREMELY mean?
EXTREMELY adverb- (degree) To an extreme degree.