Old jailers ignoring last of warden's failures (7)
I believe the answer is:
turkeys
'failures' is the definition.
(turkey is a kind of failure)
I cannot understand how the rest of the clue works.
(Other definitions for turkeys that I've seen before include "Movie flops" , "Birds with fan-shaped tails" , "Theatre flops or Christmas birds" , "The birds for cranberry sauce, or theatre flops" .)