Begin new life (5)
I believe the answer is:
being
'life' is the definition.
(thesaurus)
'begin new' is the wordplay.
'new' is an anagram indicator.
'begin' anagrammed gives 'BEING'.
(Other definitions for being that I've seen before include "Human, perhaps" , "Living thing" , "See 9" , "Existing" , "A living creature" .)