Crossword Genius

Bird goes round picking up drugs and used rubber (7)

Ross

I believe the answer is:

retread

I'm a little stuck... Click here to teach me more about this clue!

'bird' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for retread that I've seen before include "modified tyre" , "what may be spare" , "film much the same as the one before" , "Second-hand tyre" , "One much improved in rubber" .)

I've seen this clue in The Guardian.
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