Lack of activity among rebellious division with no leader (8)
I believe the answer is:
inaction
'lack of activity' is the definition.
(lack of action)
'among rebellious division with no leader' is the wordplay.
'among' becomes 'in' (eg among or in a group).
'rebellious division' becomes 'faction' (eg faction of a political party).
'with no leader' means to remove the first letter.
'faction' with its first letter taken away is 'action'.
'in'+'action'='INACTION'
(Other definitions for inaction that I've seen before include "Immobility" , "Dormancy" , "Sluggishness" , "Idleness - fighting" , "Stasis" .)