Brisk stiffener? Get iced drinks (9)
I believe the answer is:
energetic
'brisk' is the definition.
(similar in meaning)
'stiffener? get iced drinks' is the wordplay.
'drinks' indicates the answer is hidden within the clue (words in the clue have absorbed the answer).
'ENERGETIC' is hidden in the letters of 'stiffener get iced'.
(Other definitions for energetic that I've seen before include "Showing great activity" , "High-powered" , "Involving great activity" , "Forceful, vigorous" , "'Animated, full of life (9)'" .)