'Sovereign Bakeries' failing, remain closed down (6)

I believe the answer is:

kaiser

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

'sovereign' is the definition.
(I know that Kaiser is a type of Kaiser)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for kaiser that I've seen before include "Austrian bigwig" , "Emperor of Austria or Germany until 1918" , "Former German emperor" , "Ruler over empire" , "Old German emperor like Bill" .)

I've seen this clue in The Telegraph.

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