Bounds beyond which one cannot go (6)
I believe the answer is:
limits
'bounds beyond which one cannot go' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for limits that I've seen before include "Curtails" , "Boundaries or furthest reaches" , "Bounds beyond which one cannot go" , "Boundaries, points beyond which something cannot continue" , "Boundaries or restrictions" .)