Plant trees, by the sound it (5)
I believe the answer is:
furze
'plant' is the definition.
The answer is an example.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for furze that I've seen before include "Another word for gorse" , "Prickly shrub" , "Whin" , "Bushy growth" , "one shrub" .)