Clue: He sips any cocktail that's hard and fruitless (9)
Answer: SISYPHEAN
Explanation: Definition: hard and fruitless
(HE SIPS ANY)* – from Sisyphus in Greek mythology, who was punished by having to push a huge boulder up a hill every day, only for it to fall down again at the end. I had to check which way round the I and Y came in the word.