Deathless, timeless and bad (7)
I believe the answer is:
immoral
'bad' is the definition.
(synonyms)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for immoral that I've seen before include "Ethically unprincipled" , "dishonest" , "Unprincipled or debauched" , "Evil" , "Unscrupulous" .)