Drug made from hemp and iron (8)
I believe the answer is:
morphine
'drug' is the definition.
(morphine is a kind of drug)
'from hemp and iron' is the wordplay.
'from' indicates anagramming the letters (from the letters).
'and' is a charade indicator (letters next to each other) (I've seen this in other clues).
'hemp' after 'iron' is 'ironhemp'.
'ironhemp' anagrammed gives 'MORPHINE'.
'made' acts as a link.
(Other definitions for morphine that I've seen before include "Powerful pain-reliever" , "Pain-relieving opiate" , "Pain-easing opiate" , "Pain-killing drug" , "Nip Homer in the bud and you'll get a powerful painkiller" .)