A tree that's cared about (5)
I believe the answer is:
cedar
'a tree' is the definition.
(cedar is a kind of tree)
'cared about' is the wordplay.
'about' indicates anagramming the letters.
'cared' anagrammed gives 'CEDAR'.
'that's' acts as a link.
(Other definitions for cedar that I've seen before include "Tree (Lebanese?)" , "Cypress-like tree" , "Fragrant conifer" , "may have needles?" , "Raced around a mighty tree" .)