Agent is one out for the count (7)
I believe the answer is:
sleeper
I believe this clue is a double definition.
'agent' is the first definition.
(a sleeper is a type of secret agent)
'is one out for the count' is the second definition.
('out for the count' means asleep)
(Other definitions for sleeper that I've seen before include "Railway tie" , "Supporting block on railway track" , "Long-inactive secret agent" , "Rail track supporter" , "Brace to support rail on track" .)