Sincerely, seriously (9)
I believe the answer is:
earnestly
I believe this clue is a double definition.
'sincerely' is the first definition.
(I've seen this before)
'seriously' is the second definition.
(I know that seriously can be written as earnestly)
(Other definitions for earnestly that I've seen before include "Showing serious intent" , "with heart and soul" , "Showing commitment" , "Sincerely and seriously" , "how Wilde character may be acted?" .)