You folks in the Southern US putting down Yankee friend (4)
I believe the answer is:
ally
'friend' is the definition.
(an ally is a friend or supporter)
'you folks in the southern us putting down yankee' is the wordplay.
I cannot really understand how this works, but
'yankee' could be 'y' (phonetic alphabet: alpha, bravo, charlie etc.) and 'y' is found within the answer.
The remaining letters 'all' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ally that I've seen before include "couple?" , "A friendly and reliable country" , "Join forces with" , "Supporter in a conflict" , "mate" .)