Totally bewildered (8)
'totally bewildered' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for at a loss that I've seen before include "Puzzled - below cost" , "Perplexed - no profit in it" , "Completely puzzled, with no idea at all" , "Puzzled, bewildered" , "how incompetent companies can operate" .)