I approve of the girl drinking vodka, ultimately — same again! (4,4)
I believe the answer is:
hear hear
'i approve' is the definition.
'the girl drinking vodka ultimately same again' is the wordplay.
'the girl' becomes 'her' (**).
'drinking' indicates putting letters inside.
'ultimately' indicates one should take the final letters.
'same again' indicates the doubling of some letters.
The last letter of 'vodka' is 'a'.
'her' placed around 'a' is 'hear'.
'hear' doubled is 'HEAR HEAR'.
'of' acts as a link.
(Other definitions for hear hear that I've seen before include "Well said!" , "Expression of whole-hearted agreement" , "expressed approval" , "exclaiming repeatedly" , "Agreed" .)