### Clue: Do I take drug, on turning up to get some protein? (5,4)
### Answer: AMINO ACID 
 ### Explanation: Definition: some protein
 { [AM I …?](do I …?) ON(take/use) ACID(short for LSD, a hallucinogenic drug) } **with reversal of**(… turning up, in a down clue) **its** "ON".
Defn: …/a building block of a protein.