Approve of sellers, not very European (7)
I believe the answer is:
endorse
'approve of' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for endorse that I've seen before include "Docket" , "Support (with signature)" , "Red ones (anag.)" , "Champion" , "Give backing to" .)