Crossword Genius

Where the junk dealers go all metric? (5,4)

Ross

I believe the answer is:

scrap yard

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

'dealers go all metric?' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'where the junk' is the wordplay.
I cannot quite understand how this works, but
'junk' could be 'crap' (I've seen this in another clue) and 'crap' is located in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in the Evening Standard.
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