For sailor, fetch butt (6)
I believe the answer is:
target
'butt' is the definition.
(I know that butt can be written as target)
'for sailor fetch' is the wordplay.
I cannot really see how this works, but
'sailor' could be 'tar' (slang term for a sailor) and 'tar' is found within the answer.
'fetch' could be 'get' (synonyms) and 'get' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for target that I've seen before include "Aimpoint" , "Goal, objective" , "Goal; victim" , "Object to be aimed at" , "Select for attack" .)