Fatter Christmas treat that's in Greek (7)

I believe the answer is:

pudgier

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'fatter' is the definition.
('pudgy' can be similar in meaning to 'fat')

'christmas treat that's in greek' is the wordplay.
'christmas treat' becomes 'pud' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'that's' becomes 'ie'.
'in' is an insertion indicator.
'greek' becomes 'gr' (abbreviation for Greek).
'ie' placed within 'gr' is 'gier'.
'pud'+'gier'='PUDGIER'

Can you help me to learn more?

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

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