Allergic rhinitis (3,5)
I believe the answer is:
hay fever
'allergic rhinitis' is the definition.
(hay fever is a kind of allergic rhinitis)
This is the entire clue.
(Other definitions for hay fever that I've seen before include "Coward created this" , "Allergic affliction" , "Pollinosis" , "Heavy ref with sneezing ailment" , "Seasonal rhinitis" .)