Change popular recreational drug for opiate (8)
I believe the answer is:
morphine
'opiate' is the definition.
(thesaurus)
'change popular recreational drug' is the wordplay.
'change' becomes 'morph' (morphing is a kind of changing).
'popular recreational drug' becomes 'ine' (I can't explain this - if you can you should believe this answer much more).
'morph'+'ine'='MORPHINE'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for morphine that I've seen before include "Pain-easing opiate" , "Pain-killing drug" , "Sedative derived from opium" , "Pain-relieving opiate" , "Powerful pain-reliever" .)