Vexed about YMCA moving tree (8)
I believe the answer is:
sycamore
'tree' is the definition.
(I know that sycamore is a type of tree)
'vexed about ymca moving' is the wordplay.
'vexed' becomes 'sore' (I've seen this in another clue).
'about' is an insertion indicator.
'moving' indicates an anagram (letters are moved around).
'ymca' anagrammed gives 'ycam'.
'sore' placed around 'ycam' is 'SYCAMORE'.
(Other definitions for sycamore that I've seen before include "Tree for the odd Rose Macy" , "European maple" , "Timber producer" , "Mr O'Casey is in the tree" , "Tree with two-winged fruit" .)