Crossword Genius

Coin collectors for avaricious botanist? (5,5)

Ross

I believe the answer is:

piggy banks

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

'coin collectors' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Maybe you can see an association between them that I don't see?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

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