Tree harsh old American disposed of in a song (9)
I believe the answer is:
araucaria
'tree' is the definition.
(araucaria is a kind of tree)
'harsh old american disposed of in a song' is the wordplay.
I cannot really see how this works, but
'american' could be 'a' (common abbreviation - e.g. in organisation names) and 'a' is present in the answer.
'a' is found in the answer.
'song' could be 'aria' (piece of music in an opera) and 'aria' is present in the answer.
The remaining letters 'ruc' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for araucaria that I've seen before include "puzzle for primates?" , "Coniferous tree" , "Evergreen" , "Monkey puzzle tree - Guardian cryptic crossword setter" , "Monkey puzzle tree (or Chile pine)" .)