It's wicked to live it up (4)
I believe the answer is:
evil
'it's wicked' is the definition.
(similar in meaning)
'live it up' is the wordplay.
'live' anagrams to 'EVIL'.
Though, I am not sure how this is indicated.
'to' is the link.
Can you help me to learn more?
(Other definitions for evil that I've seen before include "Wicked - vice" , "Badness, depravity" , "Demonic" , "Morally corrupt" , "Profoundly wicked" .)