Hideaway in garden (3)

I believe the answer is:

den

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'hideaway' is the definition.
(synonyms)

'garden' is the wordplay.
'DEN' is hidden within the letters.
But, I am unsure how the hidden word is indicated.

'in' is the link.

Can you help me to learn more?

(Other definitions for den that I've seen before include "Private office" , "Animals' shelter" , "Miserable place" , "Cave" , "Hiding place" .)

I've seen this clue in The Mirror.

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