Brilliant spectacle opening up over Etna perhaps (7)

I believe the answer is:

pageant

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'brilliant spectacle' is the definition.
'pageant' can be an answer for 'spectacle' (I've seen this before). I'm not certain of the 'brilliant' bit.

'opening up over etna perhaps' is the wordplay.
'opening' becomes 'gap' (synonyms).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'perhaps' is an anagram indicator.
'gap' in reverse letter order is 'pag'.
'etna' is an anagram of 'eant'.
'pag'+'eant'='PAGEANT'

Can you help me to learn more?

(Other definitions for pageant that I've seen before include "Spectacular display" , "Spectacular parade" , "Magnificent parade" , "Series of tableaux etc" , "elaborate display" .)

I've seen this clue in The Globe and Mail.

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