Also, in short, a mixed drink (6)
I believe the answer is:
shandy
'a mixed drink' is the definition.
(I've seen this before)
'also in short' is the wordplay.
'also' becomes 'and' (both can mean in addition).
'in' indicates putting letters inside.
'short' becomes 'shy' (I've seen this in other clues).
'and' put inside 'shy' is 'SHANDY'.
(Other definitions for shandy that I've seen before include "Beer/lemonade mixture" , "A misture of ale and lemonade" , "Beer/lemonade drink" , "Weakly-alcoholic drink" , "Drink made of beer and lemonade" .)