Beats old attorney to a drink (4,4)
I believe the answer is:
club soda
'to a drink' is the definition.
(I've seen this before)
'beats old attorney' is the wordplay.
'beats' becomes 'clubs' (I can't justify this - if you can you should give a lot more credence to this answer).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'attorney' becomes 'DA' (District Attorney).
'clubs'+'o'+'da'='CLUB SODA'
Can you help me to learn more?
(Other definitions for club soda that I've seen before include "Fizzy drink" , "Carbonated water (US)" .)