Gold vehicle in song about coniferous tree (9)
I believe the answer is:
araucaria
'coniferous tree' is the definition.
(araucaria is a kind of coniferous tree)
'gold vehicle in song' is the wordplay.
'gold' becomes 'au' (Au is the chemical symbol for gold).
'vehicle' becomes 'car' (car is a kind of vehicle).
'in' means one lot of letters goes inside another.
'song' becomes 'aria' (aria is a kind of song).
'au'+'car'='aucar'
'aucar' placed inside 'aria' is 'ARAUCARIA'.
'about' is the link.
(Other definitions for araucaria that I've seen before include "puzzle for primates?" , "Evergreen" , "Monkey puzzle tree - Guardian cryptic crossword setter" , "Monkey puzzle tree (or Chile pine)" , "Coniferous tree" .)