Power to stop, say (6)
I believe the answer is:
weight
This might be a double definition.
'power' is the first definition.
(thesaurus)
'stop say' is the second definition.
'weight' can be an answer for 'say' (thesaurus). I'm not sure about the 'stop' bit.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for weight that I've seen before include "Significance" , "Gravitational pull" , "Relative heaviness" , "The property of heaviness, measure of mass" , "Import" .)