Pie filler to chop up heart (9)

I believe the answer is:

mincemeat

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'pie filler' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'chop up heart' is the wordplay.
'chop up' becomes 'mince' (mincing is a kind of chopping up).
'heart' becomes 'meat' (synonyms).
'mince'+'meat'='MINCEMEAT'

'to' is the link.

Can you help me to learn more?

(Other definitions for mincemeat that I've seen before include "Spiced mixture of raisins, candied peel, apples etc" , "pie-fillers" , "Tart ingredient" , "Christmas pie filling" , "Christmas pie filler" .)

I've seen this clue in The Sun.

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