Old king earl left in indebted state? (8)

I believe the answer is:

ethelred

I'm a little stuck... Click here to teach me more about this clue!

'old king' is the definition.
(as in thelred the Unready, medieval king)

'earl left in indebted state?' is the wordplay.
'earl' becomes 'e'.
'left' becomes 'l' (common abbreviation).
'in' means one lot of letters goes inside another.
'indebted state?' becomes 'thered' (I can't explain this - if you can you should believe this answer much more).
'l' going within 'thered' is 'thelred'.
'e'+'thelred'='ETHELRED'

Can you help me to learn more?

(Other definitions for ethelred that I've seen before include "Early English king" , "King nicknamed the Unready" , "Baleen used to stiffen corsets, etc" , ""Unready" English king" , "Alfred the Great's brother and predecessor, d. 871 -- the elder (anag)" .)

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.