Presides when moved to scatter (8)
I believe the answer is:
disperse
'to scatter' is the definition.
('disperse' can be a synonym of 'scatter')
'presides when moved' is the wordplay.
'when moved' indicates an anagram.
'presides' is an anagram of 'DISPERSE'.
(Other definitions for disperse that I've seen before include "Broadcast" , "Scatter, break up" , "Presides so as to scatter" , "'Break up, spread out (8)'" , "Cause to separate and go in different directions" .)