Duke in defeat backed Henry say (5)
I believe the answer is:
'henry say' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'duke in defeat backed' is the wordplay.
'duke' becomes 'd' (abbreviation).
'in' is an insertion indicator.
'defeat' becomes 'rout' (routing is a kind of defeating).
'backed' says the letters should be written backwards.
'd' placed within 'rout' is 'rodut'.
'rodut' reversed gives 'TUDOR'.
Can you help me to learn more?
(Other definitions for tudor that I've seen before include "Elizabeth I of England was of this royal family" , "Former English royal house" , "Member of royal family" , "Name of English royal family during 16th century" , "A royal house of England" .)