Busy type coming to river for drink (4)
I believe the answer is:
beer
'for drink' is the definition.
(beer is a kind of drink)
'busy type coming to river' is the wordplay.
'busy type' becomes 'bee' (I've seen this in other clues).
'coming to' says to put letters next to each other.
'river' becomes 'r' (abbreviation for river).
'bee'+'r'='BEER'
(Other definitions for beer that I've seen before include "It may be 13 across-ed!" , "Perhaps bitter" , "Brewery product" , "Fermented malt and hops" , "Fermented alcoholic drink" .)