The most common and most likely answer to this crossword clue is the 8 letter word VENOMOUS
I've seen this crossword clue in Financial Times
V
E
N
O
M
O
U
S
More clues leading to the result VENOMOUS
- Very obese queen's dropped acid
- Malevolent rodent almost beneath cooker, moving over
- Very very fat shirking Republican leader is toxic
- Spiteful single victor returns ahead of sumo wrestling
- Spiteful tennis player hiding old working method
- Moon almost crashed into planet with malignant effect
- It’s poisonous, move us on out of the way
- Snake-like tailless rodent under cooking oven
- Spiteful move on us squelched
- Polaveno mouse contains toxin
Buddy explains!

The straight part
We know that "toxic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case toxic = venomous.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 VENOMOUS mean?
VENOMOUS adjective- Full of venom.
- Toxic; poisonous.
- Noxious; evil.
- Malignant; spiteful; hateful.
- Producing venom (a toxin usually injected into an enemy or prey by biting or stinging) in glands or accumulating venom from food.
- Powerful