Plot hit, causing chaos (6)
I believe the answer is:
bedlam
'chaos' is the definition.
('bedlam' can be a synonym of 'chaos')
'plot hit' is the wordplay.
'plot' becomes 'bed' (bed is a kind of plot).
'hit' becomes 'lam' (to 'lam' means to hit hard).
'bed'+'lam'='BEDLAM'
'causing' acts as a link.
(Other definitions for bedlam that I've seen before include "Blamed for noisy uproar" , "Blames for uproar" , "Chaos - former asylum" , "Ambled (anag)" , "Very noisy confused place" .)