Dietary concern for Arabian? Getting iron on top of vitamins in hospital for what's an allergic reaction!
I believe the answer is:
hay fever
'allergic reaction' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for hay fever that I've seen before include "Pollinosis" , "Coward play" , "Seasonal rhinitis" , "Rhinitis resulting from an allergic reaction to pollen" , "summer glums?" .)