Odd aura about song, evergreen (9)
I believe the answer is:
araucaria
'evergreen' is the definition.
(I've seen this before)
'odd aura about song' is the wordplay.
'odd' indicates anagramming the letters.
'about' becomes 'c' (abbreviation for circa).
'song' becomes 'aria' (aria is a kind of song).
'aura' with letters rearranged gives 'arau'.
'arau'+'c'+'aria'='ARAUCARIA'
(Other definitions for araucaria that I've seen before include "Evergreen" , "Monkey puzzle tree - Guardian cryptic crossword setter" , "Coniferous tree" , "Monkey puzzle tree (or Chile pine)" , "puzzle for primates?" .)