Potable extract of valerian (3)
I believe the answer is:
ale
'potable' is the definition.
(ale is a kind of potable)
'extract of valerian' is the wordplay.
'extract of' indicates the answer is hidden within the clue (I've seen this in other clues).
'ALE' is hidden in the letters of 'valerian'.
(Other definitions for ale that I've seen before include "Beerlike beverage" , "Beer consumed in sales" , "Alcoholic drink" , "A drink; sounds like become ill" , "Intoxicating drink" .)