The most common and most likely answer to this crossword clue is the 10 letter word MORDACIOUS
I've seen this crossword clue in The Times
M
O
R
D
A
C
I
O
U
S
Buddy explains!

The straight part
We know that "Vitriolic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vitriolic = mordacious.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 MORDACIOUS mean?
MORDACIOUS adjective- Biting, causing a physical bite or sting; corrosive
- Sharp or caustic in style or tone.
- Prone to biting, aggressive (of an animal etc.).
- Sharp in intent, sarcastic