Failure; counterfeit (3)
I believe the answer is:
dud
This clue is a double definition.
'failure' is the first definition.
(I know that dud is a type of failure)
'counterfeit' is the second definition.
(I've seen this before)
(Other definitions for dud that I've seen before include "Defective" , "'Flop, turkey (3)'" , "Useless, doesn't work - a palindrome" , "Fake -- failure" , "Useless, ineffective" .)