Note preceding Martin Luther? (8)
I believe the answer is:
reformer
'luther?' is the definition.
(I've seen this before)
'note preceding martin' is the wordplay.
'note' becomes 're' (as in do-re-mi).
'preceding martin' becomes 'former' (I can't justify this - if you can you should give a lot more credence to this answer).
're'+'former'='REFORMER'
Can you help me to learn more?
(Other definitions for reformer that I've seen before include "One who changes or improves, say, an organisation" , "One dealing with abuses" , "Luther, for one" , "campaigner for change" , "Luther, perhaps" .)