Acorn tree I mulched for pleasure (10)

I believe the answer is:

recreation

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'for pleasure' is the definition.
(thesaurus)

'acorn tree i mulched' is the wordplay.
'acorn tree i' can be anagrammed to 'RECREATION'.
But, I'm not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for recreation that I've seen before include "Sort of ground" , "Play" , "pleasurable leisure activity" , "free time" , "fun" .)

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

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