Drug (6)
(Other definitions for opiate that I've seen before include "Drug such as morphine" , "Drug made from poppy" , "painkiller" , "something stupefying" , "one soporific" .)
(Other definitions for heroin that I've seen before include "Class A drug" , "Hard drug" , "junk" , "Highly addictive drug madefrom morphine" , "Highly addictive illegal drug" .)
'drug' is the definition.
(opium is a kind of drug)
This is all the clue.
(Other definitions for opium that I've seen before include "analgesic" , "Number" , "The stuff of wars" , "Duller" , "Narcotic derived from poppies" .)
'drug' is the definition.
(I've seen this before)
This is the entire clue.
(Another definition for beta blocker that I've seen is " Drug used to treat high blood pressure".)