___ Wednesday (3)
'wednesday?' is the definition.
(I know that wednesday can be written as Midweek)
This is all the clue.
(Other definitions for midweek that I've seen before include "Wednesday (or thereabouts)" , "Tuesday to Thursday?" , "Normal working day(s)" .)
(Other definitions for ash that I've seen before include "Burnt remains; tree" , "Wooden" , "Tree; burned residue" , "Tree with keys" , "Part of forest" .)