Clue: Doctor's instruction has carrier admitting refusal to return weapon (2,2,4)
Answer: DO NO HARM
Explanation: Doctor's instruction has carrier admitting refusal to return weapon (2,2,4)
**<=**(**HOD** (brick "carrier") *admitting* **NO** ("refusal")) [*to return*] + **ARM** ("weapon"), so **D(ON)OH-ARM