Good girl that can hold her drink (5)
I believe the answer is:
glass
'good girl that can hold her drink' is the definition.
'glass' can be an answer for 'good girl' (I've seen this in other clues). I'm unsure of the rest of the definition.
'good girl' is the wordplay.
'good' becomes 'g' (abbreviation).
'girl' becomes 'lass' (lass is a kind of girl**).
'g'+'lass'='GLASS'
(Other definitions for glass that I've seen before include "Transparent solid" , "(Material used in) mirror" , "Greenhouse material" , "Translucent, usually transparent, material" , "Telescope perhaps" .)