Girl called up by Charlie? (5)

I believe the answer is:

della

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'girl' is the definition.

'called up by charlie?' is the wordplay.
'DELLA' is hidden backwards in amongst the letters.
But, I'm not sure how this is indicated.

Can you help me to learn more?

(Another definition for della that I've seen is " - - Street (Perry Mason)".)

I've seen this clue in the Evening Standard.

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