Partly explain a rule about astronomers’ inspiration (6)
I believe the answer is:
urania
'astronomers' inspiration' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'partly explain a rule about' is the wordplay.
'partly' says the answer is hidden in the clue (part of the clue is used).
'about' says the letters should be written backwards.
'ainaru' is hidden in the letters of 'explain a rule'.
'ainaru' in reverse letter order is 'URANIA'.
Can you help me to learn more?
(Other definitions for urania that I've seen before include "Muse of astronomy" , "One of the Muses" .)