Dispose of deranged acid eater (9)
I believe the answer is:
eradicate
'dispose of' is the definition.
(I've seen this before)
'deranged acid eater' is the wordplay.
'deranged' indicates an anagram.
'acid'+'eater'='acideater'
'acideater' is an anagram of 'ERADICATE'.
(Other definitions for eradicate that I've seen before include "Destroy completely" , "Exterminate, extinguish" , "Extinguish, wipe out" , "Stamp out, remove all traces of" , "Excise" .)