Situation in which progress is impossible (7)
I believe the answer is:
impasse
'situation in which progress is impossible' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for impasse that I've seen before include "Situation in which no progress can be made" , "block" , "Lack of movement" , "Inescapable perdicament, dilemma" , "Deadlock or stand-off" .)