Please turn page before my nursing lecture, with no content for star theorist (7)

I believe the answer is:

ptolemy

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

'nursing lecture with no content for star theorist' is the definition.
I can't tell whether this defines the answer.

'please turn page before my' is the wordplay.
'please turn' becomes 'tole' (I can't explain this - if you can you should believe this answer much more).
'page' becomes 'p'.
'before' means one lot of letters go next to another.
'tole' after 'p' is 'ptole'.
'ptole'+'my'='PTOLEMY'

Can you help me to learn more?

(Other definitions for ptolemy that I've seen before include "Greek astronomer; Greco-Egyptian ruler" , "Egyptian king or astronomer" , "Ancient astronomer" , "Alexandrian astronomer" , "Egyptian ruler; Greek astronomer" .)

I've seen this clue in The Independent.

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