3D image of queen, say, on throne (3,4)
I believe the answer is:
cat scan
'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".)