Mark's little girl (3)

I believe the answer is:

dot

This clue is a double definition.

'mark's' is the first definition.
(dotting is a kind of marking)

'little girl' is the second definition.
(I've seen this before)

(Other definitions for dot that I've seen before include "Full stop, period or tittle" , "Internet punctuation mark" , "Shorter of the two signals used in Morse code" , "Little mark" , "Long-ago year?" .)

I've seen this clue in the Evening Standard.

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