Examinations eliminate toxin, surprisingly, as a cause of memory defect (7)
I believe the answer is:
amnesia
'a cause of memory defect' is the definition.
I can't tell whether this defines the answer.
'examinations eliminate toxin surprisingly' is the wordplay.
'eliminate' indicates named letters should be taken away.
'surprisingly' indicates anagramming the letters (a surprising ordering of the letters).
'examinations' with 'toxin' taken out is 'eamains'.
'eamains' with letters rearranged gives 'AMNESIA'.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for amnesia that I've seen before include "Am I sane? (anag)" , "memory problem" , "Inability to remember" , "Severe forgetfulness" , "Complaint" .)