17a. A new sound added to a recording (7) O?E?T??
8d. Officially certified copy of a court order etc
(7). E?T?A?T
18d. Things that are bigger or better than usual (7)
??E?E?S
20d. Where in Scotland unusual fern flourished
Without a bit of greenery (7). R?N?R?W
I thought it may be Renfrew .