The most common and most likely answer to this crossword clue is the 8 letter word MIGHTILY
I've seen this crossword clue in The Daily Telegraph
M
I
G
H
T
I
L
Y
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 = mightily.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 MIGHTILY mean?
MIGHTILY adverb- In a mighty manner; with strength or force.
- Thoroughly; entirely.