The most common and most likely answer to this crossword clue is the 9 letter word REBUTTING
I've seen this crossword clue in The Daily Telegraph
R
E
B
U
T
T
I
N
G
More clues leading to the result REBUTTING
Buddy explains!

The straight part
We know that "Denying" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case denying = rebutting.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 REBUTTING mean?
REBUTTING verb- To drive back or beat back; to repulse.
- To deny the truth of something, especially by presenting arguments that disprove it.