Crossword Genius

There's no smoke without it (7)

Ross

I believe the answer is:

tobacco

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'it' is the definition.
The definition suggests a singular noun which matches the answer.

I can't explain the remainder of the clue.

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(Other definitions for tobacco that I've seen before include "Weed dangerous to health" , "Dangerous plant" , "make a cot cob from this plant" , "(Treated leaves of) American plant" , "Leaves to smoke" .)

I've seen this clue in The Globe and Mail.
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