In which to see the royal toilet? (6-4)

I believe the answer is:

throne-room

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

'in which to see' is the definition.
I know nothing about this answer so I can't judge whether this works.

'royal toilet?' is the wordplay.
'royal' becomes 'throne' (I can't justify this - if you can you should give a lot more credence to this answer).
'toilet?' becomes 'room' (toilet is a kind of room).
'throne'+'room'='THRONE-ROOM'

'the' acts as a link.

Can you help me to learn more?

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

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