Tree almost got animal agitated (8)
I believe the answer is:
magnolia
'tree' is the definition.
(magnolia is a kind of tree)
'almost got animal agitated' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'agitated' indicates an anagram.
'got' with its final letter taken away is 'go'.
'go'+'animal'='goanimal'
'goanimal' is an anagram of 'MAGNOLIA'.
(Other definitions for magnolia that I've seen before include "Spring-flowering tree" , "ornamental tree" , "Creamy-white colour" , "Creamy white, shrub" , "Tree with creamy-white flowers" .)