Crossword Genius

How might gardeners become rich? (4,2,3,5)

Ross

I believe the answer is:

rake in the money

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

'how might gardeners' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'rich?' is the wordplay.
I cannot really understand how this works, but
'rich?' could be 'inthemoney' (I've seen this in another clue) and 'inthemoney' is found in the answer.
The remaining letters 'rake' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

'become' is the link.

Can you help me to learn more?

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