Incumbent on US TV series in eleventh-hour situation (4,2,3,4)
I believe the answer is:
down to the wire
'us tv series in eleventh-hour situation' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'incumbent on' is the wordplay.
I cannot really see how this works, but
'on' could be 'to' and 'to' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for down to the wire that I've seen before include "approaching deadline" , "Up to the very last moment" .)