Distress is something quite clear to the audience (4)
I believe the answer is:
pain
'distress' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for pain that I've seen before include "Sensation of acute discomfort" , "Physical hurt" , "Suffering, distress" , "French bread?" , "Mental distress" .)