Thelma Barlow's part as 'Queen' (3)

I believe the answer is:

mab

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

'queen' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see an association between them that I can't see?

'thelma barlow's part' is the wordplay.
'part' says the answer is hidden in the clue.
'MAB' is hidden within 'thelma barlow'.

'as' is the link.

Can you help me to learn more?

(Another definition for mab that I've seen is " Queen--, fairy mentioned in Romeo and Juliet".)

I've seen this clue in the Evening Standard.

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