He tries to prevent ill feeling (6)
I believe the answer is:
doctor
This could be a double definition.
'he tries to prevent' is the first definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'ill feeling' is the second definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
Can you help me to learn more?
(Other definitions for doctor that I've seen before include "One treats the ill" , "Eg, surgeon" , "Medical worker or holder of highest university degree" , "Medical professional or university don" , "Licensed medical practitioner" .)