More ostentatious party involving one (7)

I believe the answer is:

showier

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'more ostentatious' is the definition.
('showy' can be similar in meaning to 'ostentatious')

I don't understand the rest of the clue.

(Other definitions for showier that I've seen before include "More ostentatious" , "more conspicuous" , "Flasher" .)

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

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