Last word before indent motivated header change (9)
I believe the answer is:
amendment
'change' is the definition.
(amendment is a kind of change)
'last word before indent motivated header' is the wordplay.
I cannot really understand how this works, but
'last' could be 't' (I've seen this in other clues) and 't' is located in the answer.
'word' could be 'amen' (I have seen 'Word of agreement' mean 'amen' so perhaps 'word' could also mean 'amen') and 'amen' is found in the answer.
'before' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for amendment that I've seen before include "A qualification" , "maybe fifth taken by US criminal" , "Revision" , "Corrective treatment" , "Correction" .)