The most common and most likely answer to this crossword clue is the 9 letter word NOTORIOUS
N
O
T
O
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I
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S
More clues leading to the result NOTORIOUS
- Infamous old port protected by other people?
- I love travelling on tours to house of ill-repute
- Hitchcock film noir out - so gruesome
- Flagrant lack of right-wingers mostly out to replace English
- Infamous head of occupied port seized by other people?
- Infamous rejection of Olympic city by American?
- Infamous Conservative briefly installed in Number Ten, useless
- Tricked! Root in middle of house of ill repute!
- Awfully famous old picture?
- Widely known and bad attack I soon rout
Buddy explains!

The straight part
We know that "Known" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case known = notorious.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 NOTORIOUS mean?
NOTORIOUS adjective- Widely known, especially for something negative; infamous.