Digging is tedious (6)
I believe the answer is:
boring
This could be a double definition.
'digging' is the first definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'tedious' is the second definition.
(I know that tedious can be written as boring)
'is' acts as a link.
Can you help me to learn more?
(Other definitions for boring that I've seen before include "Making holes" , "flat" , "Tedious, of no interest" , "Drilling can be tedious" , "Drilling - it's monotonous" .)