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

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

Please turn page before my nursing lecture, with no content for star theorist L <ectur> E (“with no content” means all but first and letters are dropped) in [PTO (=please turn page, i.e. please turn over) + MY]; the reference is to the Alexandrian mathematician and astronomer Ptolemy, who lived from circa 100-170AD