Takes in heroin and arsenic (3)
I believe the answer is:
has
'takes in' is the definition.
(I've seen this in another clue)
'heroin and arsenic' is the wordplay.
'heroin' becomes 'H' (H is a slang term for heroin).
'and' says to put letters next to each other.
'arsenic' becomes 'As' (As is the chemical symbol for arsenic).
'h'+'as'='HAS'
(Other definitions for has that I've seen before include "Enjoys" , "Owns, holds" , "Cheats" , "Possesses or owns" , "suffers from" .)