Planet finally completes a revolution (6)

I believe the answer is:

saturn

'planet' is the definition.
(Saturn is an example)

'finally completes a revolution' is the wordplay.
'finally' suggests the final letters.
'revolution' becomes 'turn' (I've seen this in another clue).
The final letter of 'completes' is 's'.
's'+'a'+'turn'='SATURN'

(Other definitions for saturn that I've seen before include "Sixth planet from the sun" , "Planet with concentric rings" , "One of the 1 across" , "Giant planet" , "Nearest ringed planet" .)

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.