Confirmed about tree (3)
I believe the answer is:
fir
'tree' is the definition.
(fir is a kind of tree)
'confirmed about' is the wordplay.
'about' says the answer is hidden in the clue (the clue goes around or about the answer).
'FIR' is hidden in the letters of 'confirmed'.
(Other definitions for fir that I've seen before include "Kind of cone-bearing tree" , "Tree with cones" , "Evergreen tree for Irish men?" , "Tree for Irishmen" , "Coniferous tree" .)