Content to leave demure aunt terribly flushed, getting changed (9)
'changed' is the definition.
(denaturing is a kind of changing)
'content to leave demure aunt terribly flushed' is the wordplay.
'content to leave' means to remove the middle letters (the contents of the word are removed).
'terribly' indicates an anagram.
'flushed' becomes 'red' (synonyms).
'demure' with its centre taken out is 'de'.
'aunt' anagrammed gives 'natu'.
'getting' is the link.