Diffusions lost heart to original lawgiver (7)

I believe the answer is:

osmoses

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'diffusions' is the definition.
(I know this)

'lost heart to original lawgiver' is the wordplay.
'heart' indicates the central letters.
'to' is a charade indicator (letters next to each other).
'original lawgiver' becomes 'moses' (Moses handed down the Ten Commandments. I am not sure about the 'original' bit.).
The middle letters of 'lost' are 'os'.
'os'+'moses'='OSMOSES'

Can you help me to learn more?

(Another definition for osmoses that I've seen is " Causes change gradually".)

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

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