Times Cryptic Jumbo Crossword 1090

[dofray]

Top right corner has me beaten, help would be appreciated to finish. I would also ask if the answer could be parsed as I like to know how the right answer is come by.
9D Correspond with former nurse about shade (3-5). S?????E?
11D Objectors may take it as a special case (9). E?????I?N. Could this be exception or exclusion?
12D French novelist with son in superior position(4). S??? Could this be SAND?
16A Somali, perhaps given twernty-four hours in a prison (6). ??R????
20A Misuse land? Perhaps Chief Constable gets run in! (8). ?V???R??
Many thanks in advance. Some of letters could bed wrong, but I am sure someone will put me right.

[bibblebub]

9d: sea-green
11d: exception
12d: Sand
16a: African
20a: overcrop

[bibblebub]

just to add

11d: objectors take exception to something
12d: with = AND, son in superior position = put S first

[kettledrum]

9d agree inside SEN
16a Fri(day) inside a can

[dofray]

Thanks Bibblebub and Kettledrum you are both wonderful. Its a lovely day in the South, hope same with you. Have a good day.

[swannupmanship]

9d sea green

[swannupmanship]

20A Could well be overcrop: overcop with r - runs

[lynbrown]

Sea green? How?

[shoota]

See best answer Lyn

[bibblebub]

correspond = AGREE
with former nurse about = put S.E.N. outside

State Enrolled Nurse

[kettledrum]

Agree = correspond

with SEN = State Enrolled Nurse 'about'