Sneeze: and what I need for it when heard? (7)

I believe the answer is:

atishoo

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'sneeze' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for atishoo that I've seen before include "Sound made on expiration" , "report of involuntary escape from trap?" , "Word to be sneezed at" , "25 sound" , "Sneezing sound" .)

I've seen this clue in The Telegraph.

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