Diabolical
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">diabolical</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that diabolical can be written as fiendish)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for fiendish that I've seen before include "Finished (anag) - demonic" , "This Sudoku" , "like some Sudokus" , "Extremely cruel" , "Diabolic" .)
(Other definitions for satanic that I've seen before include "Relating to the devil" , "Devilish, like Blake's mills" , "Bad" , "Fiendish" , "Devilish (as Blake's 18)" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">diabolical</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that diabolical can be written as demonic)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for demonic that I've seen before include "Wicked" , "Cruel like the devil" , "diabolical" , "Resembling evil spirits" , "Devilish" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">diabolical</span>' is the definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for evil that I've seen before include "Malign" , "Extremely bad" , "very naughty" , "Great wickedness" , "A live sort of badness" .)