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 quite understand how this works, but
'fellows' could be 'ff' and 'ff' is present in the answer.
an anagram of 'sure' is 'suer' which is within the left over letters.
This accounts for all the letters.
This may be the basis of 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" .)