Threaten a mischief-maker with death perhaps (6)
I believe the answer is:
impend
'threaten' is the definition.
(I've seen this before)
'a mischief-maker with death perhaps' is the wordplay.
'a mischief maker' becomes 'imp' (I've seen this in other clues).
'with' says to put letters next to each other.
'death perhaps' becomes 'end' (death is a kind of end).
'imp'+'end'='IMPEND'
(Other definitions for impend that I've seen before include "Become imminent" , "Be about to take place" , "(Of a bad thing) loom" , "Threaten - be about to happen" , "seen to be around the corner" .)