Tree with 'winged' seeds (4)
'tree with winged seeds' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ash that I've seen before include "Dusty residue of a fire" , "Tree; cinders" , "Common tree" , "End of fire" , "Remnant from fire" .)
(Other definitions for acer that I've seen before include "Tree of maple family" , "Care about the maple?" , "Tree with winged fruit" , "Tree or shrub of the maple genus" , "ornamental tree" .)