Change the last word Democrat intended in speech (9)
I believe the answer is:
amendment
'change' is the definition.
(amendment is a kind of change)
'the last word democrat intended in speech' is the wordplay.
'the last word' becomes 'amen' (I've seen this before).
'democrat' becomes 'd'.
'intended' becomes 'meant' (meaning is a kind of intending).
'in speech' indicates a 'sounds like' (homophone) clue.
'meant' is a homophone of 'ment'.
'amen'+'d'+'ment'='AMENDMENT'
(Other definitions for amendment that I've seen before include "Statement added to or revising a document" , "A qualification" , "maybe fifth taken by US criminal" , "Correction" , "Revision" .)