Pull bovine animal across rear of barn (4)
I believe the answer is:
yank
'pull' is the definition.
(yanking is a kind of pulling)
'bovine animal across rear of barn' is the wordplay.
'bovine animal' becomes 'yak'.
'across' is an insertion indicator.
'rear of' says to take the final letters.
The final letter of 'barn' is 'n'.
'yak' going around 'n' is 'YANK'.
(Other definitions for yank that I've seen before include "Sharp tug" , "American - jerk" , "Pull sharply" , "Tug sharply - American" , "Pull hard suddenly" .)