Had to accept upturns in less potent drink (5)
I believe the answer is:
decaf
'drink' is the definition.
(decaffeinated coffee)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for decaf that I've seen before include "Non-alcoholic drink" , "Less stimulating coffee?" , "Coffee without the kick?" , "Style of coffee" , "Cup substitute missing kick" .)