Very cowardly over avoiding the last round of fire (6)
I believe the answer is:
volley
'round of fire' is the definition.
(eg a volley of bullets)
I can't explain the remainder of the clue.
(Other definitions for volley that I've seen before include "A flight of missiles" , "Simultaneous discharge of a number of firearms" , "Salvo (of bullets)" , "Tennis, football, shot" , "Lovely kind of tennis stroke" .)