Discharge of artillery in ovals more or less (5)

I believe the answer is:

salvo

I'm a little stuck... Click here to teach me more about this clue!

'discharge' is the definition.
(I've seen this before)

'artillery in ovals more or less' is the wordplay.
'ovals' can be anagrammed to 'SALVO'.
Though, I'm unsure how the anagram is indicated.

'of' is the link.

Can you help me to learn more?

(Other definitions for salvo that I've seen before include "Aussie evangelist" , "Sudden round of applause" , "Simultaneous discharge of fire" , "A simultaneous salute of guns" , "Simultaneous discharge of artillery" .)

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

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