Design goes into small drink (7)
I believe the answer is:
martini
'drink' is the definition.
(martini is a kind of drink)
'design goes into small' is the wordplay.
'design' becomes 'art' (design is an art).
'goes into' means one lot of letters goes inside another.
'small' becomes 'mini' (short for miniature).
'art' put inside 'mini' is 'MARTINI'.
(Other definitions for martini that I've seen before include "Cocktail of gin and dry vermouth" , "James Bond's drink of choice" , "Gin or vodka with dry vermouth" , "Cocktail made with gin or vodka and vermouth" , "In glass, one's dry" .)