4 down, colour and (shade) you'd associate with the Senior Service, (4,4) ?a?y???i.
15 down, constructed so well as to be impervious to moisture.(10) ??t?l?i?h?.
17 down, cylindrical wheels of cheese, (8) t?u?k?e?.
14 across, Deepest; most worthless, (6) ???s?.