Old astronomer is the focus of collegial renewal (7)

I believe the answer is:

galileo

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'old astronomer' is the definition.
'galileo' can be an answer for 'astronomer' (I've seen this before). I'm not certain of the 'old' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for galileo that I've seen before include "was in trouble with the Inquisition" , "victim of Inquisition" , "He said Eppur si muove (But it does move)" , "Pioneer scientist" , "Famous scientist" .)

I've seen this clue in the Sydney Morning Herald.

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