Old army boy could become queen (6,4)

I believe the answer is:

bloody mary

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'queen' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.

'old army boy could become' is the wordplay.
'could become' indicates an anagram.
'old'+'army'+'boy'='oldarmyboy'
'oldarmyboy' with letters rearranged gives 'BLOODY MARY'.

Can you help me to learn more?

(Other definitions for bloody mary that I've seen before include "something to drink" , "Queen regarded unfavourably" , "The Red Queen" , "Nickname of Henry VIII's first daughter" , "killing Queen?" .)

I've seen this clue in The Independent.

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