Declaring cannon gun I fired (10)

I believe the answer is:

announcing

'declaring' is the definition.
('announce' can be a synonym of 'declare')

'cannon gun i fired' is the wordplay.
'fired' indicates anagramming the letters (I've seen this in other clues).
'cannon'+'gun'+'i'='cannonguni'
'cannonguni' anagrammed gives 'ANNOUNCING'.

(Another definition for announcing that I've seen is " Declaring".)

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

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