Drink drunk in haste containing boron (8)
I believe the answer is:
absinthe
'drink' is the definition.
(absinthe is a kind of drink)
'drunk in haste containing boron' is the wordplay.
'drunk' indicates an anagram.
'containing' indicates putting letters inside.
'boron' becomes 'b' (synonyms).
'in'+'haste'='inhaste'
'inhaste' with letters rearranged gives 'asinthe'.
'asinthe' going around 'b' is 'ABSINTHE'.
(Other definitions for absinthe that I've seen before include "Liqueur originally containing wormwood" , "Strong green alcoholic drink" , "Green aniseed liqueur" , "Green wormwood drink" , "Green liqueur flavoured with wormwood and anise" .)