Liqueur Italian knocked back with a girl (3,5)
I believe the answer is:
tia maria
'liqueur' is the definition.
(I've seen this before)
'italian knocked back with a girl' is the wordplay.
'italian' becomes 'it'.
'knocked back' shows that the letters should be reversed in order.
'with' is a charade indicator (letters next to each other).
'girl' becomes 'maria' ().
'it' backwards is 'ti'.
'ti'+'a'+'maria'='TIA MARIA'
(Other definitions for tia maria that I've seen before include "Coffee-flavoured trademarked liqueur" , "Coffee-flavoured rum drink" , "Coffee-flavour liqueur" , "After-dinner liqueur" , "Rum-based coffee liqueur" .)