What Luther refused to do about a religious treatise (7)

I believe the answer is:

retract

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'what luther refused to do' is the definition.
The definition suggests a singular noun but the answer is not.

'about a religious treatise' is the wordplay.
'about' becomes 're' (regarding).
'a religious treatise' becomes 'tract' (I've seen this before).
're'+'tract'='RETRACT'

Can you help me to learn more?

(Other definitions for retract that I've seen before include "Withdraw, take back" , "Eat one's words" , "Cancel" , "Take back or draw in" , "Sheathe" .)

I've seen this clue in The Globe and Mail.

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