The most common and most likely answer to this crossword clue is the 10 letter word DIPHTHERIA
I've seen this crossword clue in The Daily Telegraph
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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.
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Crossword Answer definitions
DIPHTHERIA noun- A serious infectious disease which causes inflammation of mucous membranes of the upper respiratory tract caused by Corynebacterium diphtheriae.