Crossword Genius

3D image of queen, say, on throne (3,4)

Ross

I believe the answer is:

cat scan

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'3d' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'image of queen say on throne' is the wordplay.
'image of queen say' becomes 'cats' (I can't justify this - if you can you should believe this answer much more).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'throne' becomes 'can' (synonyms).
'cats'+'can'='CAT SCAN'

Can you help me to learn more?

(Another definition for cat scan that I've seen is " Three dimensional image".)

I've seen this clue in The Independent.
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