Cinders (6)
(Other definitions for embers that I've seen before include "Glowing residue of fire" , "Glowing coals" , "Vestiges of fire" , "Dying coals in fire" , "Remains of coal fire" .)
'cinders' is the definition.
(cinders can mean ashes)
This is all the clue.
(Other definitions for ash that I've seen before include "One [TYPE OF TREE]" , "Residue after burning" , "Wooden" , "Tree with winged seeds" , "Tree; fire residue" .)