Alcohol and drugs consumed by banker on vacation (4)
I believe the answer is:
beer
'alcohol' is the definition.
(I know that beer is a type of beer)
'drugs consumed by banker on vacation' is the wordplay.
'drugs' becomes 'ee' (an abbreviation for ecstasy written twice).
'consumed by' is an insertion indicator (inserted letters get consumed).
'on vacation' means to remove the middle letters (after the inside letters have vacated the word).
'banker' with its centre removed is 'br'.
'ee' placed inside 'br' is 'BEER'.
'and' acts as a link.
(Other definitions for beer that I've seen before include "The standard English drink" , "Hopped drink" , "Brewery product" , "Fermented malt and hops" , "Drink with a head" .)