The first Stateside anti-drug agency's purpose (4)
I believe the answer is:
idea
'purpose' is the definition.
(idea is a kind of purpose)
'the first stateside anti-drug agency's' is the wordplay.
'IDEA' is hidden within the letters.
However, I'm uncertain how this is indicated.
Can you help me to learn more?
(Other definitions for idea that I've seen before include "intellectual product" , "Inkling" , "Flash of inspiration?" , "It comes to mind" , "Plato's Form is" .)