Mishap (8)
'mishap' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for accident that I've seen before include "Eg, car crash" , "Fortune" , "Dance tic leading to mishap" , "Unforeseen mishap" , "Collision" .)
(Other definitions for slip that I've seen before include "Clay, water mix; fielder" , "Minor error; garment" , "Sole lapse" , "Drop" , "Mistake (of tongue or pen)" .)