The most common and most likely answer to this crossword clue is the 10 letter word OBLITERATE
I've seen this crossword clue in Financial Times
O
B
L
I
T
E
R
A
T
E
More clues leading to the result OBLITERATE
- Hide from man who's left school educated
- Get rid of scholar no longer showing benefits of education?
- Get rid of religious type keeping unorthodox rite
- Bear toilet that's nasty? No, do this to it
- Knock out bore with a title after being punched
- Remove all traces of old tribe tale? Out of order!
- Nothing scholarly about book’s cover
- Vicious bile to assess and eliminate
- Destroy old book, well-read
- Get rid of former student who can read
Buddy explains!
The straight part
We know that "Knock out" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case knock out = obliterate.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 OBLITERATE mean?
OBLITERATE verb- To remove completely, leaving no trace; to wipe out; to destroy.