Tramps gather bottles in bottom box (6,7)

I believe the answer is:

ghetto blaster

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'bottom box' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'tramps gather bottles' is the wordplay.
'gather bottles' can be anagrammed to 'GHETTO-BLASTER'.
Though, I am unsure how this is indicated.

'in' acts as a link.

Can you help me to learn more?

(Other definitions for ghetto blaster that I've seen before include "Powerful portable radio or CD player" , "Large portable radio and CD player" , "Powerful portable stereo" , "Large music machine" , "Large portable stereo" .)

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

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