Oscar-winning Vietnam film directed by Oliver Stone (7)
I believe the answer is:
platoon
'oliver stone' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'oscar-winning vietnam film directed by' is the wordplay.
I cannot really understand how this works, but
'oscar' could be 'o' (phonetic alphabet: alpha, bravo, charlie etc.) and 'o' is found within the answer.
'by' could be 'at' and 'at' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for platoon that I've seen before include "Group of soldiers" , "Soldiers under lieutenant" , "detail" , "part of company" , "Company's subdivision" .)