A bright one like Muriel? (5)

I believe the answer is:

spark

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'muriel?' is the definition.
(I know that muriel can be written as Spark)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for spark that I've seen before include "Quantity of electricity" , "Fiery particle" , "Bright flash; ignite" , "Means of ignition" , "Flicker -- provoke" .)

I've seen this clue in the Evening Standard.

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