Ancient deity - a heavyweight? (4)

I believe the answer is:

aton

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'ancient deity' is the definition.
I know nothing about this answer so I can't tell whether this works.

'a heavyweight?' is the wordplay.
'heavyweight?' becomes 'ton' (a ton weighs a lot).
'a'+'ton'='ATON'

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

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