One is so in order to listen (6)

I believe the answer is:

silent

I'm a little stuck... Click here to teach me more about this clue!

'one is so' is the definition.
I can't judge whether this definition defines the answer.

'order to listen' is the wordplay.
'order' indicates an anagram.
'listen' with letters rearranged gives 'SILENT'.

'in' is the link.

Can you help me to learn more?

(Other definitions for silent that I've seen before include "Anagram of 7 Down" , "Noiseless" , "Unspeaking" , "Dumb" , "Strange and astonishing thing" .)

I've seen this clue in the Evening Standard.

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