Corrections sent madmen off the rails (10)
I believe the answer is:
amendments
'corrections' is the definition.
(amendment is a kind of correction)
'sent madmen off the rails' is the wordplay.
'sent madmen' anagrams to 'AMENDMENTS'.
But, I am not sure how this is indicated.
Can you help me to learn more?
(Other definitions for amendments that I've seen before include "adjustments required" , "Changes to parliamentary bill" .)