Savanna tree (6)
I believe the answer is:
acacia
'savanna tree' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for acacia that I've seen before include "Tropical tree, inc. mimosa, wattle" , "Gum-yielding tree ir shrub" , "Spiny shrub with clusters of yellow or white flowers" , "Locust tree the false one" , "Wattle genus" .)