Constrains extremities (6)
I believe the answer is:
limits
This clue might be a double definition.
'constrains' is the first definition.
The answer and definition can be both related to change as well as being verbs in their -s form.
Perhaps there's a link between them I don't understand?
'extremities' is the second definition.
(limit is a kind of extremity)
Can you help me to learn more?
(Other definitions for limits that I've seen before include "Boundaries, points beyond which something cannot continue" , "Curtails" , "Sets boundaries to, restricts" , "Outer reaches" , "Biblical prophet" .)