Secrecy measure unknown in Princeton, strangely (10)

I believe the answer is:

encryption

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

'secrecy measure' is the definition.
The definition suggests a singular noun which matches the answer.

'unknown in princeton strangely' is the wordplay.
'unknown' becomes 'y' (algebra).
'in' is an insertion indicator.
'strangely' is an anagram indicator.
'princeton' is an anagram of 'encrption'.
'y' put within 'encrption' is 'ENCRYPTION'.

Can you help me to learn more?

I've seen this clue in The Guardian.

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