I don't normally have too much trouble with this one, but am completely stuck this morning ....
18a someone who can be seduced or deceived without difficulty (4,4) ??s? m??t
20a one who insists on maintaining something in its traditional form (6) p?r???
4a in cookery, served plain with parsley garnish (1,2, 6,6,) a la ?a?t?? ?h?t?l
17d of a region of ancient Egypt west of Nile delta (7) n???i?n