It may be taken to promote good feeling (8)
I believe the answer is:
medicine
This clue might be a double definition.
'it may be taken to promote' is the first definition.
The definition suggests a singular noun which matches the answer.
'good feeling' is the second definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for medicine that I've seen before include "It treats, prevents or alleviates disease" , "Laughter is said to be the best one" , "Remedy for illness" , "Curative treatment" , "It's used to treat disorders and diseases" .)