Laugh loudly in every new allergy (8)
I believe the answer is:
hayfever
'allergy' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'laugh loudly in every new' is the wordplay.
'laugh' becomes 'ha'.
'loudly' becomes 'f' (short for forte - 'loud' in music).
'in' indicates putting letters inside.
'new' indicates anagramming the letters.
'every' anagrammed gives 'yever'.
'f' inserted within 'yever' is 'yfever'.
'ha'+'yfever'='HAYFEVER'
Can you help me to learn more?
(Other definitions for hayfever that I've seen before include "intolerant reaction" , "Coward produced this" .)