Folder's loss (4)
I believe the answer is:
ante
'folder's loss' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ante that I've seen before include "Pre-deal stake" , "Gaming stake" , "Stake put up by a poker-player before receiving cards" , "Advance stake" , "Stake; before (Lat.)" .)