I'll sit on sofa going crazy, accepting SAGE's ultimate protective measure (4-9)

'i'll sit on sofa' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'going crazy accepting sage's ultimate protective measure' is the wordplay.
I cannot quite understand how this works, but
'going' could be 'on' (both can mean functioning or activated) and 'on' is found in the answer.
'measure' could be 'at' (at is a kind of measure) and 'at' is present in the answer.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?