Crossword Genius

Grinds, sounding like sheltered waterways (6)

Ross

I believe the answer is:

creaks

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

'grinds sounding like sheltered waterways' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot understand how they can define each other.

This is all the clue.

Can you help me to learn more?

(Another definition for creaks that I've seen is " Makes sound like old floorboard".)

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