Zest revolutionised hot sugary drinks (5)
I believe the answer is:
gusto
'zest' is the definition.
(synonyms)
'revolutionised hot sugary drinks' is the wordplay.
'revolutionised' is a reversal indicator.
'drinks' says the answer is hidden in the clue (words in the clue have absorbed the answer).
'otsug' is hidden in the letters of 'hot sugary'.
'otsug' backwards is 'GUSTO'.
(Other definitions for gusto that I've seen before include "Great enjoyment in doing something" , "(Corporate) emblem" , "Vigorous and enthusiastic enjoyment" , "Relish; vigour" , "exhilaration" .)