### Clue: Use less MDMA? Come on, silly, one's consumed by it! (9)
### Answer: ECONOMISE 
 ### Explanation: Definition: Use less
 **Anagram of**(…, silly) [ E(abbrev. for the drug, ecstasy, the chemical compound methylenedioxy?methamphetamine abbreviated as MDMA) + COME ON] **containing**(… consumed by it) I(Roman numeral for one)'S .