Help out when gold potty lost in bathroom? (4,3,8)

I believe the answer is:

down the plughole

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'lost in bathroom?' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'help out when gold potty' is the wordplay.
'potty' indicates an anagram.
'help'+'out'+'when'+'gold'='helpoutwhengold'
'helpoutwhengold' anagrammed gives 'DOWN THE PLUGHOLE'.

Can you help me to learn more?

I've seen this clue in The Guardian.

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