Show off about one's life to come (8)
I believe the answer is:
paradise
'life to come' is the definition.
(thesaurus)
'show off about one's' is the wordplay.
'show off' becomes 'parade'.
'about' means one lot of letters goes inside another.
'one's' becomes 'is' (roman numeral).
'parade' going around 'is' is 'PARADISE'.
(Other definitions for paradise that I've seen before include "Eden; ideal place" , "Happiness" , "perfectly happy state" , "Heaven, nirvana, Valhalla etc" , "Shangri-La?" .)