In a plot that's convoluted, is the potential killer (6)
I believe the answer is:
pistol
'the potential killer' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'in a plot that's convoluted is' is the wordplay.
'in' is an insertion indicator.
'that's convoluted' indicates an anagram.
'plot' anagrammed gives 'ptol'.
'ptol' placed around 'is' is 'PISTOL'.
Can you help me to learn more?
(Other definitions for pistol that I've seen before include "pop" , "Small firearm" , "Type of gun" , "Small gun" , "Shakespearean character" .)