Pure heroin snorted by actors with MDMA (6)
I believe the answer is:
chaste
'pure' is the definition.
('chaste' can be similar in meaning to 'pure')
'heroin snorted by actors with mdma' is the wordplay.
I cannot really see how this works, but
'heroin' could be 'h' ('H' can be a synonym of 'heroin') and 'h' is located in the answer.
'actors' could be 'cast' (I've seen this before) and 'cast' is located in the leftover letters.
A single letter 'e' remains which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for chaste that I've seen before include "Morally pure" , "Decorous" , "avoiding relations" , "Pure and inviolate" , "Untarnished" .)