The most common and most likely answer to this crossword clue is the 6 letter word RAWEST
I've seen this crossword clue in The Guardian
R
A
W
E
S
T
Buddy explains!
The straight part
We know that "Most biting" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case most biting = rawest.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 RAWEST mean?
RAWEST adjective- (of food) Not cooked.
- (of materials, products, etc.) Not treated or processed; in a natural state, unrefined, unprocessed.
- Having had the skin removed or abraded; chafed, tender; exposed, lacerated.
- New or inexperienced.
- Crude in quality; rough, uneven, unsophisticated.
- (of data) Uncorrected, without analysis.
- (of weather) Unpleasantly cold or damp.
- (of an emotion, personality, etc.) Unmasked, undisguised, strongly expressed
- Candid in a representation of unpleasant facts, conditions, etc.
- (of language) Unrefined, crude, or insensitive, especially with reference to sexual matters
- Not covered; bare; bald.