Ex-POTUS laid back early in the day with a dog he owns (5)
I believe the answer is:
obama
'ex-potus' is the definition.
(Barack Obama, former president of the US)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for obama that I've seen before include "US presidential candidate" , "44th US President" , "Leading man" , "one with top job in Washington" , "Trump's predecessor" .)