Unexpectedly named by Queen, one changing for the better? (7)
I believe the answer is:
amender
'one changing for the better?' is the definition.
'unexpectedly named by queen' is the wordplay.
'unexpectedly' indicates an anagram.
'by' means one lot of letters go next to another.
'queen' becomes 'er' (abbreviation for Elizabeth Regina**).
'named' with letters rearranged gives 'amend'.
'amend'+'er'='AMENDER'
(Other definitions for amender that I've seen before include "Editor" , "agent of change" .)