Popular characters in 20 across not working (8)
I believe the answer is:
inactive
'not working' is the definition.
(I've seen this before)
'popular characters in 20' is the wordplay.
'popular' becomes 'in'.
'characters in c0' becomes 'active' (I can't explain this - if you can you should give a lot more credence to this answer).
'in'+'active'='INACTIVE'
'across' acts as a link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for inactive that I've seen before include "Passive, doing nothing" , "Idle, showing no movement" , "Resting" , "Not moving/working" , "Not doing anything, passive" .)