I've finished, but am unsure of how these answers work.
18 D. House poor Mark somewhere in London (8)
d?e?l?n?
I've got 'dwelling', house, but can't parse the rest.
4 D. Facing put in place after work on back of blouse (8)
?p?o?i?e
I've got 'opposite'/facing - but got myself all tangled up with the rest. Any thoughts/explanations would be appreciated.