Crash, with "out" (4)
I believe the answer is:
conk
'crash with out' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for conk that I've seen before include "Hooter" , "Nose, head (sl.)" , "Blow" , "Nose (colloq.)" , "Nose; break down" .)