What can produce an allergic reaction? Some say Aunt Jennifer (7)
I believe the answer is:
antigen
'jennifer' is the definition.
Both the definition and answer are singular nouns.
Perhaps they are linked in a way I don't understand?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for antigen that I've seen before include "Immunity-booster" , "toxin" , "Something inducing an immune response, neat gin (anag.)" , "Substance inducing an immune response" , "Biological substance" .)