Conditions needed when there's a hedgerow to trim? (4,7)

I believe the answer is:

good weather

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'trim?' is the definition.
The answer and definition can be both states of affairs as well as being singular nouns.
Perhaps there's a link between them I don't understand?

'conditions needed when there's a hedgerow to' is the wordplay.
'a hedgerow to' anagrams to 'GOOD WEATHER'.
Though, I am not sure how the anagram is indicated.

Can you help me to learn more?

I've seen this clue in The Globe and Mail.

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