Does wrong in medicine (4)
I believe the answer is:
dose
'medicine' is the definition.
(dose is a kind of medicine)
'does wrong' is the wordplay.
'wrong' is an anagram indicator.
'does' with letters rearranged gives 'DOSE'.
'in' acts as a link.
(Other definitions for dose that I've seen before include "Medicinal quantity" , "Measure (med.)" , "Give drugs to (a person)" , "Measured portion of medicine" , "some Viagra, perhaps?" .)