Fizzy drink small, easy to reach (6)
I believe the answer is:
shandy
'fizzy drink' is the definition.
(fizzy alcoholic drink)
'small easy to reach' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'easy to reach' becomes 'handy' (I've seen this in another clue).
's'+'handy'='SHANDY'
(Other definitions for shandy that I've seen before include "Beer/lemonade mixture" , "Beer and lemonade mixture" , "Weakly-alcoholic drink" , "Lemonade-beer drink" , "mixed drink" .)