Old one's in to raise work with puny margins for drug supplier (5,5)

I believe the answer is:

opium poppy

'drug supplier' is the definition.
(opium is derived from the opium poppy)

I can't explain the remainder of the clue.

(Other definitions for opium poppy that I've seen before include "drug supplier" , "Growing drug source?" .)

I've seen this clue in The Times.

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