A god to swear by? (7)
I believe the answer is:
jupiter
'a god' is the definition.
(Jupiter is an example)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for jupiter that I've seen before include "to which Tom Towers contributed" , "Planet - Roman equivalent of Zeus" , "Largest planet in our solar system" , "Chief of the Gods, by Jove" , "Heavenly body" .)