Consumed, bit of lemonade sucked up (4)
I believe the answer is:
used
'consumed' is the definition.
(I've seen this in another clue)
'bit of lemonade sucked up' is the wordplay.
'bit of' says the answer is hidden in the clue.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'desu' is hidden within 'lemonade sucked'.
'desu' backwards is 'USED'.
(Other definitions for used that I've seen before include "Sued (anag.)" , "Scottish expert" , "Employed - exploited" , "Prepossessed, perhaps" , "Second-hand; consumed" .)