He's difficult to cope with is as much as you can grasp (7)
I believe the answer is:
handful
'can grasp' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'he's difficult to cope with is as much as you' is the wordplay.
I cannot really understand how this works, but
'with' could be 'and' and 'and' is found in the answer.
'you' could be 'u' (commonly used in online communication) and 'u' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for handful that I've seen before include "Small number - difficult person or thing" , "Small number or amount" , "Someone hard to control" , "children that are difficult to control" , "Smattering" .)