6d. Cast down (5) M?U?T
7d. You want to be in it (4) N?E?
14a. It is barred (6) ?R?L?E (Could be Grille??)
20a. Exits? (8) O???O??? (Could be Outdoors??)
18d. Of course they're better devices (5) T?T?S assuming 20a is Outdoors (3rd letter is mutual)
16d. Enough to prevent parting without meeting (6) ?U?R?M
21a. A direction to lower a boat (4) ?C?W