Correction about setter's demise (9)
I believe the answer is:
remedying
'correction about setter's demise' is the definition.
I can't judge whether this defines the answer.
'about setter's demise' is the wordplay.
'about' becomes 're' (regarding).
'setter' becomes 'me' (the setter of the clue).
'demise' becomes 'dying' (synonyms).
're'+'me'+'dying'='REMEDYING'
Can you help me to learn more?
(Other definitions for remedying that I've seen before include "Putting right (an undesirable situation)" , "sorting out" .)