First Lady is very into ecstasy pills (3)
I believe the answer is:
eve
'first lady' is the definition.
(Biblical first woman)
'very into ecstasy pills' is the wordplay.
'very' becomes 'v' (common abbreviation).
'into' indicates putting letters inside.
'ecstasy' becomes 'E' (informal term for the drug).
'pills' becomes 'E' (E is short for ecstasy).
'e'+'e'='ee'
'v' going inside 'ee' is 'EVE'.
'is' is the link.
(Other definitions for eve that I've seen before include "comes before Jan. 1st" , "Adam & - -" , "Woman in a happy place" , "Day before (an event)" , "when it gets dark" .)