A drink - Ben has it as a cocktail (8)
I believe the answer is:
absinthe
'a drink' is the definition.
(absinthe is a kind of drink)
'ben has it as a cocktail' is the wordplay.
'ben has it' anagrams to 'ABSINTHE'.
However, I'm not sure how the anagram is indicated.
Can you help me to learn more?
(Other definitions for absinthe that I've seen before include "Green wormwood drink" , "Bitter liqueur" , "intoxicant" , "alcohol" , "French liqueur" .)