A large drink, so to speak, for girl (7)
I believe the answer is:
abigail
'girl' is the definition.
'a large drink so to speak' is the wordplay.
'large' becomes 'big' ('big' can be a synonym of 'large').
'drink' becomes 'ale' (I've seen this before).
'so to speak' indicates a 'sounds like' (homophone) clue.
'ale' sounds like 'ail'.
'a'+'big'+'ail'='ABIGAIL'
'for' is the link.
(Other definitions for abigail that I've seen before include "Lady's maid (once); David's wife (I. Sam.)" , "Woman's name - old lady's maid" , "Girl's name" , "lady!" , "Missing party girl" .)