Some easterners taken back (6)
I believe the answer is:
astern
'back' is the definition.
(I've seen this before)
'some easterners taken' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'ASTERN' is hidden in the letters of 'easterners taken'.
(Other definitions for astern that I've seen before include "Towards back of boat" , "Ran set (anag.)" , "following behind vessel" , "Behind (a boat)" , "Toward the tail of a vessel" .)