Cryptic crossword clue
Former Lord Chancellor took title of ‘doctor’ and finally ‘knight’ 7

The most common and most likely answer to this crossword clue is the 7 letter word MORDRED

I've seen this crossword clue in Independent
M
O
R
D
R
E
D

Buddy explains!

The straight part
We know that "knight (of the round table)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case knight (of the round table) = mordred.
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.

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