Threaten mischief-maker with death! (6)
I believe the answer is:
impend
'threaten' is the definition.
(I've seen this in another clue)
'mischief-maker with death' is the wordplay.
'mischief maker' becomes 'imp' (I've seen this in other clues).
'with' means one lot of letters go next to another.
'death' becomes 'end' (synonyms).
'imp'+'end'='IMPEND'
(Other definitions for impend that I've seen before include "(Of a bad thing) loom" , "Be imminent or about to happen" , "Be about to take place" , "seen to be around the corner" , "Be looming" .)