The most common and most likely answer to this crossword clue is the 10 letter word IMMACULATE
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result IMMACULATE
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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 IMMACULATE mean?
IMMACULATE adjective- Having no stain or blemish; spotless, undefiled, clear, clean, pure.
- Lacking spots, blotches, or other markings; spotless; unspotted.