Hercules, say, one sent to prison in mythical time (6,3)
I believe the answer is:
heroic age
'mythical time' is the definition.
'heroic age' can be an answer for 'time' (I have seen 'Legendary time' mean 'heroic age' so perhaps 'time' could also mean 'heroic age'). I am unsure of the 'mythical' bit.
'hercules say one sent to prison' is the wordplay.
'hercules say' becomes 'hero' (I can't explain this - if you can you should give a lot more credence to this answer).
'one' becomes 'i' (Roman numeral).
'sent to' says to put letters next to each other.
'prison' becomes 'cage' (cage is a kind of prison).
'hero'+'i'+'cage'='HEROIC AGE'
'in' acts as a link.
Can you help me to learn more?
(Another definition for heroic age that I've seen is " Legendary time".)