Drink just for Frank (9)
I believe the answer is:
downright
'frank' is the definition.
(I've seen this before)
'drink just' is the wordplay.
'drink' becomes 'down' (to down something can mean to drink it quickly).
'just' becomes 'right' (associated in meaning).
'down'+'right'='DOWNRIGHT'
'for' acts as a link.
(Other definitions for downright that I've seen before include "Utter, complete" , "Absolutely!" , "Blatant" , "rank" , "blunt" .)