Paint Sid knocked over with outburst of anger (9)
I believe the answer is:
distemper
'paint' is the definition.
(distempering is a kind of painting)
'sid knocked over with outburst of anger' is the wordplay.
'knocked over' says the letters should be written in reverse.
'with' is a charade indicator (letters next to each other).
'outburst of anger' becomes 'temper' (I've seen this before).
'sid' written backwards gives 'dis'.
'dis'+'temper'='DISTEMPER'
(Other definitions for distemper that I've seen before include "Paint; canine disease" , "Paint for walls; disease" , "Colourful coat" , "problem for pet" , "Paint; animal disease" .)