### Clue: Pure heroin snorted by actors with MDMA (6)
### Answer: CHASTE 
 ### Explanation: Definition: Pure
 H(abbrev. for "heroin") **contained in**(snorted by) CAST(the group of actors in a play or movie) **plus**(with) E(abbrev. for "Ecstasy"/the drug whose chemical name is abbreviated to MDMA).