Flip. as a coin (4)
I believe the answer is:
toss
'flip as a coin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for toss that I've seen before include "What to do with a pancake and a caber" , "Flip up into the air - coin or salad" , "Leave decision to chance" , "decision-making process" , "Fall from horse" .)