Wednesday? (7)
'wednesday?' is the definition.
(I know that wednesday can be written as Midweek)
This is the entire 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" .)