The most common and most likely answer to this crossword clue is the 5 plus 5 letter word SUPER DUPER
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More clues leading to the result SUPER DUPER
Buddy explains!

The straight part
We know that "Extraordinary" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case extraordinary = super duper.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 SUPER DUPER mean?
SUPER DUPER adjective- Very excellent; truly great.
- Complete, total, absolute.