'Zero' variety dandies periodically drink (9)
I believe the answer is:
orangeade
'drink' is the definition.
(orangeade is a kind of drink)
'zero variety dandies periodically' is the wordplay.
'zero' becomes 'O' (O resembles 0).
'variety' becomes 'range' (range can mean a wide variety).
'periodically' indicates alternate letters (letters must be selected 'every so often').
The alternate letters of 'dandies' are 'ade'.
'o'+'range'+'ade'='ORANGEADE'
(Other definitions for orangeade that I've seen before include "Bubbly drink" , "Fruity drink" , "Soft citrus drink" , "Fruit drink" , "Pop" .)