Current device succeeded in dispersing rioters (8)
I believe the answer is:
resistor
'current device' is the definition.
'succeeded in dispersing rioters' is the wordplay.
'succeeded' becomes 's' (genealogical abbreviation).
'in' indicates putting letters inside.
'dispersing' is an anagram indicator.
'rioters' anagrammed gives 'resitor'.
's' going within 'resitor' is 'RESISTOR'.
(Other definitions for resistor that I've seen before include "Electrical component" , "It obstructs current" , "Electrical device" , "Circuit component" , "Electronic component" .)