That nobleman started at a previous stage (5,2)
I believe the answer is:
early on
'at a previous stage' is the definition.
I can't judge whether this defines the answer.
'that nobleman started' is the wordplay.
'that' becomes 'yon' (archaic term meaning 'that').
'nobleman' becomes 'earl' (member of the nobility).
'started' means one lot of letters go next to another.
'yon' put after 'earl' is 'EARLY ON'.
Can you help me to learn more?
(Other definitions for early on that I've seen before include "right at the start" , "Quite soon in the proceedings" , "Previously" , "In the first stages" , "Ere much time passed" .)