Tons invested in stock, flipping American junk (8)

I believe the answer is:

detritus

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'junk' is the definition.
(synonyms)

'tons invested in stock flipping american' is the wordplay.
'tons' becomes 't'.
'invested in' becomes 'tired' (I can't explain this - if you can you should give a lot more credence to this answer).
'stock' is an insertion indicator (some letters contain or stock others).
'flipping' says the letters should be written in reverse.
'american' becomes 'US' (abbreviation for United States).
't' going into 'tired' is 'tirted'.
'tirted' written backwards gives 'detrit'.
'detrit'+'us'='DETRITUS'

Can you help me to learn more?

(Other definitions for detritus that I've seen before include "Debris, rubble" , "Waste, debris" , "Debris, dust" , "waste material" , "Remains" .)

I've seen this clue in The Times.

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