Unpretentious old medicine (6)
I believe the answer is:
simple
This could be a double definition.
'unpretentious' is the first definition.
(similar in meaning)
'old medicine' is the second definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
Can you help me to learn more?
(Other definitions for simple that I've seen before include "Unpretentious" , "Elementary" , "Mean" , "Plant with medicinal properties" , "Easily done" .)