Race around tree (4)
I believe the answer is:
acer
'tree' is the definition.
(acer is a type of tree)
'race around' is the wordplay.
'around' is an anagram indicator.
'race' is an anagram of 'ACER'.
(Other definitions for acer that I've seen before include "Care about the maple?" , "Plant" , "Tree with winged fruit" , "Care about this tree" , "Tree or shrub of the maple genus" .)