Sure, though wrong, the fellows in it experience pain (6)
I believe the answer is:
suffer
'pain' is the definition.
(thesaurus)
'sure though wrong the fellows in it experience' is the wordplay.
I cannot really understand how this works, but
'fellows' could be 'ff' (an abbreviation for fellow written twice) and 'ff' is located in the answer.
an anagram of 'sure' is 'suer' which is within the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for suffer that I've seen before include "Experience (something bad)" , "Undergo pain or hardship" , "Endure pain or discomfort" , "Experience hurt" , "Undergo pain or grief" .)