Tree trunk (4)
'tree trunk' is the definition.
(term for the trunk of a tree)
This is the entire clue.
(Other definitions for bole that I've seen before include "Tree trunk" , "Tree-trunk" .)
(Other definitions for caber that I've seen before include "One taking a toss" , "Trunk tossed in the Highlands" , "What's tossed" , "One Highlanders toss" , "Pole tossed as a test of strength" .)