Where tallyman's boss has legal trade? (4,3,7)

I believe the answer is:

over the counter

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'where tallyman's boss has legal trade?' is the definition.
The definition suggests a singular noun which matches the answer.

This is all the clue.

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(Other definitions for over the counter that I've seen before include "unrestricted sale" , "sale system" , "Purchasable without prescription" , "way some drugs are sold" , "By ordinary retail purchase" .)

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

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