The most common and most likely answer to this crossword clue is the 10 letter word INCREDIBLE
I've seen this crossword clue in Independent
I
N
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Buddy explains!

The straight part
We know that "Amazing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case amazing = incredible.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 INCREDIBLE mean?
INCREDIBLE adjective- Too implausible to be credible; beyond belief; unbelievable.
- Amazing; astonishing; awe-inspiring.
- Marvellous; profoundly affecting; wonderful.