Crossword Genius

Where tallyman's subordinates have illicit trade? (5,3,7)

Ross

I believe the answer is:

under the counter

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'trade?' is the definition.
Both the definition and answer are adjectives. Maybe you can see a link between them that I can't see?

I cannot understand how the rest of the clue works.

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(Other definitions for under the counter that I've seen before include "Serving only favoured customers" , "Sold illicitly" , "Secretly" , "Surreptitiously" , "avoiding controls" .)

I've seen this clue in the Sydney Morning Herald.
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