Show experts gallery king installed (11)

I believe the answer is:

demonstrate

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'show' is the definition.
(I know this)

'experts gallery king installed' is the wordplay.
'experts' becomes 'demons' (I can't justify this - if you can you should give a lot more credence to this answer).
'gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
'king' becomes 'R' (abbreviation for rex, king in Latin).
'installed' is an insertion indicator.
'tate' placed around 'r' is 'trate'.
'demons'+'trate'='DEMONSTRATE'

Can you help me to learn more?

(Other definitions for demonstrate that I've seen before include "Prove - protest" , "March" , "Make a public protest" , "Show or display" , "Take part in public protest" .)

I've seen this clue in The Daily Mail.

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