Don't invest in dodgy pocketknives with Russian money (6)

I believe the answer is:

kopeck

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

'don't' is the definition.
Both the answer and definition are singular nouns.
Perhaps there's a link between them I don't understand?

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for kopeck that I've seen before include "little Russian money" , "Russian coin" , "One hundred of these make one rouble" , "One-hundredth of a rouble" , "Russian copper" .)

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

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.