Suddenly striking canopy family head possesses (7,2)

I believe the answer is:

dawning on

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'suddenly striking' is the definition.
Although both the answer and definition are present participle verbs, I cannot see how one could define the other.

'canopy family head possesses' is the wordplay.
'canopy' becomes 'awning' (awning is a kind of canopy).
'family head' becomes 'don' (I've seen this in another clue).
'possesses' means one lot of letters goes inside another.
'awning' going into 'don' is 'DAWNING ON'.

Can you help me to learn more?

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

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