Thus get attorney drink (4)
I believe the answer is:
soda
'drink' is the definition.
(I know that soda is a type of soft drink)
'thus get attorney' is the wordplay.
'thus' becomes 'so' (synonyms).
'get' says to put letters next to each other.
'attorney' becomes 'DA' (District Attorney).
'so'+'da'='SODA'
(Other definitions for soda that I've seen before include "kind of water" , "fizz" , "Alkaline substance used in cleaning, drinks etc" , "pressurised liquid" , "Accompaniment to whisky" .)