Hero satisfied to imprison god (4)
I believe the answer is:
eros
'god' is the definition.
(I know that Eros is a Greek deity)
'hero satisfied to imprison' is the wordplay.
'to imprison' says the answer is hidden in the clue (the answer is imprisoned by the clue).
'EROS' is hidden within 'hero satisfied'.
(Other definitions for eros that I've seen before include "capital statue" , "Cupid, son of Aphrodite" , "I'm in a circus in London" , "Piccadilly 14 ac statue" , "Sore about love god" .)