Amateur, not English, could show pain (6)
I believe the answer is:
trauma
'pain' is the definition.
(trauma can mean pain or distress)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for trauma that I've seen before include "Shock with long-lasting effects" , "hurt" , "Bodily or mental shock" , "Emotional shock, long-lasting" , "Physical injury (medical)" .)