Serious Australian sextons? (12)

I believe the answer is:

gravediggers

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'serious australian sextons?' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe there's an association between them I don't understand?

'serious australian sextons?' is the wordplay.
'serious' becomes 'grave' (both can mean solemn).
'australian' becomes 'digger' (term for an Australian soldier in World War I).
'sextons?' becomes 's' (this could be a standard abbreviation of which I'm unaware).
'grave'+'digger'+'s'='GRAVEDIGGERS'

Can you help me to learn more?

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

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