Crossword Genius

Putting a number in an envelope saying "Authorship Unknown" (4)

Ross

I believe the answer is:

anon

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

'unknown' is the definition.
(I've seen this before)

'putting a number in an' is the wordplay.
'putting a number' becomes 'no' (I can't explain this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'no' going inside 'an' is 'ANON'.

'envelope saying authorship' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for anon that I've seen before include "Presently - or unknown" , "Immediately" , "In the near future" , "soon to be written" , "Soon; unattributed" .)

I've seen this clue in the Evening Standard.
Want a hint initially instead of a full solution? Install my app