Crossword Genius

When worried headwaiter let loose with the scourer (5,4)

Ross

I believe the answer is:

steel wool

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

'scourer' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Another definition for steel wool that I've seen is " household cleaner".)

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