Tedious, fatiguing (9)
I believe the answer is:
wearisome
I believe this is a double definition.
'tedious' is the first definition.
(I know that tedious can be written as wearisome)
'fatiguing' is the second definition.
(thesaurus)
(Other definitions for wearisome that I've seen before include "Tedious, tiring" , "pestilential" , "Boring" , "Trying" , "Vexatious" .)