Coward's work that could make one sniffy

I believe the answer is:

hay fever

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'coward's work that could make one sniffy' is the definition.
'hay fever' can be an answer for 'coward's' (I've seen this before). I'm unsure of the remainder of the definition.

This is all the clue.

Can you help me to learn more?

(Other definitions for hay fever that I've seen before include "Seasonal rhinitis" , "Coward play" , "Pollinosis" , "Allergy caused by pollen, dust etc" , "summer glums?" .)

I've seen this clue in The Telegraph.

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