American who gave name to wild ox (4)
I believe the answer is:
yank
'american' is the definition.
(Yank can informally mean an American)
'gave name to wild ox' is the wordplay.
I cannot quite see how this works, but
'name' could be 'n' (common abbreviation e.g. on forms) and 'n' is located in the answer.
'ox' could be 'yak' (yak is a kind of ox) and 'yak' is located in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'who' is the link.
Can you help me to learn more?
(Other definitions for yank that I've seen before include "Countryman" , "Pull sharply" , "sudden 24D [DRAW] ?" , "Term for an American" , "Sharp tug" .)