Definitely shown to wander in extremes of pain (6)
I believe the answer is:
proven
'definitely shown' is the definition.
'proven' can be an answer for 'shown' (thesaurus). I am not sure about the 'definitely' bit.
'wander in extremes of pain' is the wordplay.
'wander' becomes 'rove' (synonyms).
'in' means one lot of letters goes inside another.
'extremes of' says to hollow out the word (remove centre letters) (only the letters at the extremes of the word).
'pain' with its centre removed is 'pn'.
'rove' going within 'pn' is 'PROVEN'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for proven that I've seen before include "Established with evidence" , "Conclusively demonstrated by evidence" , "Established beyond doubt" , "Adjective meaning demonstrated beyond doubt" .)