Dozy American general captured by foreign agent (6)
I believe the answer is:
sleepy
'dozy' is the definition.
(thesaurus)
'general captured by foreign agent' is the wordplay.
'general' becomes 'lee' (Robert E. Lee - US revolutionary commander).
'captured by' is an insertion indicator.
'foreign agent' becomes 'spy' (spy is a kind of agent. I am not sure about the 'foreign' bit.**).
'lee' placed into 'spy' is 'SLEEPY'.
'american' is the link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sleepy that I've seen before include "Ready to turn in" , "Likely to turn in" , "Soporific" , "Lethargic" , "Unwakeful" .)