What makes breeze breathe? (4)

I believe the answer is:

lisp

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But I can't explain it at all! Could you help me understand?

(Other definitions for lisp that I've seen before include "Be unable to pronounce S" , "Talk like thith" , "Thpeak like thith" , "Slight speech impediment" , "speak imperfectly" .)

I've seen this clue in The Everyman puzzle in The Observer.

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