Many quietly engaged in cunning capital investments (7)

I believe the answer is:

wimples

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

'capital investments' is the definition.
Although both the answer and definition are plural nouns, I can't see how they can define each other.

'many quietly engaged in cunning' is the wordplay.
'many' becomes 'm' (Roman numeral for a thousand).
'quietly' becomes 'p' (p for piano and quiet).
'engaged in' is an insertion indicator.
'cunning' becomes 'wiles' (I've seen this in another clue).
'm'+'p'='mp'
'mp' going within 'wiles' is 'WIMPLES'.

Can you help me to learn more?

I've seen this clue in The Globe and Mail.

Want a hint initially instead of a full solution? Install my app