Grub prepared for the monarch? (6)

I believe the answer is:

burger

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'grub prepared for the monarch?' is the definition.
I can't tell whether this defines the answer.

'grub prepared for the monarch?' is the wordplay.
'prepared' is an anagram indicator.
'for' says to put letters next to each other.
'the monarch?' becomes 'ER' (abbreviation for Elizabeth Regina, British Queen).
'grub' is an anagram of 'burg'.
'burg'+'er'='BURGER'

Can you help me to learn more?

(Other definitions for burger that I've seen before include "Fast food item" , "Meat in a bun (colloq.)" , "Fried cake of minced beef served in a bun" , "Flat disc of meat in a bun" , "snack" .)

I've seen this clue in the Evening Standard.

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