Deliberate loss (4)
I believe the answer is:
dive
'deliberate loss' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dive that I've seen before include "Submarine captain's command" , "Plunge; low bar" , "Plunge into a low haunt" , "Dip" , "Plummet" .)