Infusion over pan is steaming (9)

I believe the answer is:

pervasion

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'infusion' is the definition.
(thesaurus)

'over pan is steaming' is the wordplay.
'over pan is' anagrams to 'PERVASION'.
But, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Another definition for pervasion that I've seen is " entry?".)

I've seen this clue in The Independent.

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