Auntie has a concoction that puts one to sleep (10)
I believe the answer is:
euthanasia
'that puts one to sleep' is the definition.
'auntie has a concoction' is the wordplay.
'concoction' indicates anagramming the letters.
'auntie'+'has'+'a'='auntiehasa'
'auntiehasa' with letters rearranged gives 'EUTHANASIA'.
(Other definitions for euthanasia that I've seen before include "Painless method of killing" , "Mercy killing" .)