______ of life (6)
(Other definitions for circle that I've seen before include "Move around (something)" , "Curved figure" , "part of theatre" , "Theatre's upper tier" , "Ring-shaped figure" .)
(Other definitions for tree that I've seen before include "eg Rowan" , "eg Cedar" , "Source of wood" , "Large plant with trunk" , "- Frog; - house" .)