Girl of limited capacity (3)

I believe the answer is:

gal

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'girl of limited capacity' is the definition.
'gal' can be an answer for 'girl'. I'm not certain of the 'of limited capacity' bit.

'girl of limited capacity' is the wordplay.
'girl' becomes 'g'.
'of limited' indicates the central letters (I've seen 'limited' mean this (the limits of the word are removed)).
'capacity' becomes 'imperial gallon' (imperial gallon is a unit of capacity).
The middle letters of 'imperialgallon' are 'al'.
'g'+'al'='GAL'

Can you help me to learn more?

(Other definitions for gal that I've seen before include "Lady" , "miss" , "US female" , "Girl from American west" , "An American girl, cowboy vintage" .)

I've seen this clue in the Evening Standard.

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