Train for a bout (4)
I believe the answer is:
spar
'train for a bout' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for spar that I've seen before include "Raps with strong pole" , "Act as boxer" , "Train at boxing; mineral" , "Pole to support sails, rigging etc" , "Pole-shaped part of the rigging" .)