Crossword Genius

Revolutionary part of Ptolemaic astronomy (6)

Ross

I believe the answer is:

castro

'revolutionary' is the definition.
(I know this)

'part of ptolemaic astronomy' is the wordplay.
'part of' indicates a hidden word.
'CASTRO' can be found hidden inside 'ptolemaic astronomy'.

(Other definitions for castro that I've seen before include "Man of Cuba" , "Cuban leader, d. 2016" , "Fidel or Raul" , "Fidel or Ral" , "Old leader" .)

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