polymath

[jenniferd]

11ac An overshadowing

I?A?B???I?N

7d A genus of North American herbs

L???R?S

[ashfordshe]

liatris

[jenniferd]

Thanks for 7d answer

[ashfordshe]

11a) ADUMBRATION ??

[NILYA]

11ac I have found 'obumbration' - Act of darkening or obscuring in Webster's Revised Unabridged Dictionary 1996 Does this help?

[Kulatron]

11a I have I-U-B-A-I-N as 5d is DIURESIS and the only word I can fit is INUMBRATION but I can only find the word inumbrate in dictionaries.

[jenniferd]

Brilliant. Thank you very much. Was just coming back with a query as "ADUMBRATION" did not fit in with 4d which is PHILOCTETES the slayer of Paris.

Needed to start 11ac with an O not an A and now I can.

[jenniferd]

I have been sorting this question by telephone with a third party and she has decided she will go with INUMBRATION as this fits her other answers. Thanks to everyone who helped.