They suffer from wrongly applied pain test (8)
I believe the answer is:
patients
'they suffer from wrongly' is the definition.
The definition suggests an adverb but the answer is not.
'applied pain test' is the wordplay.
'applied' indicates anagramming the letters (apply the letters).
'pain'+'test'='paintest'
'paintest' with letters rearranged gives 'PATIENTS'.
Can you help me to learn more?
(Other definitions for patients that I've seen before include "I sent Pat into the hospital inmates" , "Doctors' customers" , "They receive medical care" , "Recipients of medical care" , "People suffering" .)