The most common and most likely answer to this crossword clue is the 6 letter word LORDLY
I've seen this crossword clue in Financial Times
L
O
R
D
L
Y
More clues leading to the result LORDLY
Buddy explains!

The straight part
We know that "magnificent" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case magnificent = lordly.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 LORDLY mean?
LORDLY adjective- Of or relating to a lord.
- Having the qualities of a lord; lordlike; noble
- Appropriate for, or suitable to, a lord; glorious.
- Proud; haughty; imperious; insolent.
- In the manner of a lord. Showing command or nobility.