No information, doctor admitted, on a hormone (8)

I believe the answer is:

androgen

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'hormone' is the definition.
(I know that androgen is a type of sex hormone)

'no information doctor admitted' is the wordplay.
'no' becomes 'ano' (I can't explain this - if you can you should give a lot more credence to this answer).
'information' becomes 'gen' (gen can informally mean information).
'doctor' becomes 'Dr' (abbreviation).
'admitted' means one lot of letters goes inside another.
'ano'+'gen'='anogen'
'anogen' going around 'dr' is 'ANDROGEN'.

'on a' is the link.

Can you help me to learn more?

(Other definitions for androgen that I've seen before include "Steroid" , "Male hormone" .)

I've seen this clue in The Independent.

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