Australian accompanying Australian in drink, not for the first time (5)
I believe the answer is:
again
'not for the first time' is the definition.
(another time)
'australian accompanying australian in drink' is the wordplay.
'australian' becomes 'A' (common abbreviation).
'accompanying' says to put letters next to each other.
'australian' becomes 'A' (common abbreviation).
'in' is an insertion indicator.
'drink' becomes 'gin' (gin is an alcoholic drink).
'a' going inside 'gin' is 'gain'.
'a'+'gain'='AGAIN'
(Other definitions for again that I've seen before include "Next time" , "Predictably perhaps" , "Repeatedly" , "Furthermore" , "Here we go ___" .)