Sincerely and seriously (9)
I believe the answer is:
earnestly
'sincerely and seriously' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for earnestly that I've seen before include "Showing commitment" , "how Wilde character may be acted?" , "Sincerely and seriously" , "In all seriousness" , "with heart and soul" .)