Sewer used for the introduction of drugs (6)
I believe the answer is:
needle
'sewer' is the definition.
(I've seen this before)
'the introduction of drugs' is the wordplay.
I cannot really understand how this works, but
'drugs' could be 'ee' (an abbreviation for ecstasy written twice) and 'ee' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'used for' acts as a link.
Can you help me to learn more?
(Other definitions for needle that I've seen before include "counter" , "Item for sewer" , "Persistently annoy" , "Thin pointer; antagonise" , "Sewing item" .)