Odes review amount of medicine (4)
I believe the answer is:
dose
'amount of medicine' is the definition.
(I've seen this before)
'odes review' is the wordplay.
'review' is an anagram indicator.
'odes' anagrammed gives 'DOSE'.
(Other definitions for dose that I've seen before include "Measure of drug" , "Measure of medicine" , "Measured amount of medicine" , "Measured portion of medicine" , "Prescribed amount of medicine" .)