Futile advice for a drug addict? (7)
I believe the answer is:
useless
'futile' is the definition.
(similar in meaning)
I don't understand the rest of the clue.
(Other definitions for useless that I've seen before include "Of no benefit" , "Without purpose" , "Ineffective" , "Not practical or constructive" , "Vain, impractical" .)