Grand opening, unfortunately, of festive occasions (5)

I believe the answer is:

galas

'festive occasions' is the definition.
(I've seen this in another clue)

'grand opening unfortunately' is the wordplay.
'opening' says to take the initial letters.
'unfortunately' becomes 'alas' ('alas' is used to express regret).
The initial letter of 'grand' is 'g'.
'g'+'alas'='GALAS'

'of' is the link.

(Another definition for galas that I've seen is " Bashes".)

I've seen this clue in the Evening Standard.

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